diff --git a/cardano-node-chairman/test/Spec/Chairman/Cardano.hs b/cardano-node-chairman/test/Spec/Chairman/Cardano.hs
index e443ea2bd07..ce64c4e0a5a 100644
--- a/cardano-node-chairman/test/Spec/Chairman/Cardano.hs
+++ b/cardano-node-chairman/test/Spec/Chairman/Cardano.hs
@@ -19,7 +19,7 @@ hprop_chairman :: H.Property
 hprop_chairman = integrationRetryWorkspace 2 "cardano-chairman" $ \tempAbsPath' -> H.runWithDefaultWatchdog_ $ do
   conf <- mkConf tempAbsPath'
 
-  let creationOptions = def{ creationNodes = cardanoDefaultTestnetNodeOptions }
+  let creationOptions = def{ creationNodes = cardanoDefaultTestnetNodesWithOptions }
   allNodes <- testnetNodes <$> createAndRunTestnet creationOptions def conf
 
   chairmanOver 120 50 conf allNodes
diff --git a/cardano-node/src/Cardano/Node/Testnet/Paths.hs b/cardano-node/src/Cardano/Node/Testnet/Paths.hs
index 9c125ffcc05..82feb6f35eb 100644
--- a/cardano-node/src/Cardano/Node/Testnet/Paths.hs
+++ b/cardano-node/src/Cardano/Node/Testnet/Paths.hs
@@ -15,6 +15,7 @@ module Cardano.Node.Testnet.Paths
   , defaultSocketPath
   , defaultConfigFile
   , defaultPortFile
+  , defaultNodeEnvFile
   ) where
 
 import           System.FilePath ((</>))
@@ -62,3 +63,7 @@ defaultConfigFile = "configuration.yaml"
 -- | Relative path to a node's port file: @defaultNodeDataDir n </> "port"@
 defaultPortFile :: Int -> FilePath
 defaultPortFile n = defaultNodeDataDir n </> "port"
+
+-- | Relative path to a node's env file: @defaultNodeDataDir n </> "env"@
+defaultNodeEnvFile :: Int -> FilePath
+defaultNodeEnvFile n = defaultNodeDataDir n </> "env"
diff --git a/cardano-testnet/cardano-testnet.cabal b/cardano-testnet/cardano-testnet.cabal
index 43b7a3cea20..395ba15ec78 100644
--- a/cardano-testnet/cardano-testnet.cabal
+++ b/cardano-testnet/cardano-testnet.cabal
@@ -84,6 +84,7 @@ library
                       , network
                       , network-mux
                       , optparse-applicative-fork
+                      , parsec
                       , ouroboros-network:{api, framework, ouroboros-network} ^>= 1.1
                       , cardano-diffusion:{api, cardano-diffusion} ^>= 1.0
                       , prettyprinter
diff --git a/cardano-testnet/changelog.d/20260506_035740_palas_testnet_specify_node_bin_per_node.md b/cardano-testnet/changelog.d/20260506_035740_palas_testnet_specify_node_bin_per_node.md
new file mode 100644
index 00000000000..2ece341692e
--- /dev/null
+++ b/cardano-testnet/changelog.d/20260506_035740_palas_testnet_specify_node_bin_per_node.md
@@ -0,0 +1,4 @@
+### Added
+
+- Added `--nodes` flag to specify node roles (SPO/relay) and custom `cardano-node` binaries per node.
+  Example: `--nodes spo,spo:node-bin=/path/to/bin,relay,relay`.
diff --git a/cardano-testnet/src/Cardano/Testnet.hs b/cardano-testnet/src/Cardano/Testnet.hs
index b965252d776..0c0059789a7 100644
--- a/cardano-testnet/src/Cardano/Testnet.hs
+++ b/cardano-testnet/src/Cardano/Testnet.hs
@@ -14,9 +14,9 @@ module Cardano.Testnet (
   TestnetRuntimeOptions(..),
   TestnetEnvOptions(..),
   RpcSupport(..),
-  TestnetNodeOptions(..),
-  NodeOptions(..),
-  cardanoDefaultTestnetNodeOptions,
+  TestnetNodesWithOptions(..),
+  NodeWithOptions(..),
+  cardanoDefaultTestnetNodesWithOptions,
   getDefaultAlonzoGenesis,
   getDefaultShelleyGenesis,
 
diff --git a/cardano-testnet/src/Parsers/Cardano.hs b/cardano-testnet/src/Parsers/Cardano.hs
index d93ec846982..7ba916f8020 100644
--- a/cardano-testnet/src/Parsers/Cardano.hs
+++ b/cardano-testnet/src/Parsers/Cardano.hs
@@ -3,6 +3,7 @@
 module Parsers.Cardano
   ( cmdCardano
   , cmdCreateEnv
+  , parseNodeSpecs
   ) where
 
 import           Cardano.Api (AnyShelleyBasedEra (..))
@@ -13,6 +14,7 @@ import           Cardano.Prelude (readMaybe)
 import           Prelude
 
 import           Control.Applicative (optional, (<|>))
+import           Control.Monad (unless)
 import           Data.Default.Class (def)
 import qualified Data.List as L
 import           Data.List.NonEmpty (NonEmpty ((:|)))
@@ -21,6 +23,9 @@ import           Data.Word (Word64)
 import           Options.Applicative (CommandFields, Mod, Parser)
 import qualified Options.Applicative as OA
 import           Options.Applicative.Types (readerAsk)
+import           Text.Parsec (char, many1, noneOf,
+                     sepBy1, string, try, (<?>), parse, eof, notFollowedBy)
+import qualified Text.Parsec as Parsec
 
 import           Testnet.Defaults (defaultEra)
 import           Testnet.Start.Cardano
@@ -55,7 +60,7 @@ pFromEnv = TestnetEnvOptions
 
 pCreationOptions :: Parser TestnetCreationOptions
 pCreationOptions = TestnetCreationOptions
-  <$> pTestnetNodeOptions
+  <$> pTestnetNodesWithOptions
   <*> pure (AnyShelleyBasedEra defaultEra)
   <*> pMaxLovelaceSupply
   <*> pNumDReps
@@ -105,21 +110,19 @@ pKesSource = OA.flag UseKesKeyFile UseKesSocket
   <>  OA.showDefault
   )
 
-pTestnetNodeOptions :: Parser TestnetNodeOptions
-pTestnetNodeOptions =
-  fmap (maybe cardanoDefaultTestnetNodeOptions mkPoolNodes) <$>
-    optional $ OA.option ensureAtLeastOne
-      (   OA.long "num-pool-nodes"
-      <>  OA.help "Number of pool nodes. Note this uses a default node configuration for all nodes."
-      <>  OA.metavar "COUNT"
-      )
+pTestnetNodesWithOptions :: Parser TestnetNodesWithOptions
+pTestnetNodesWithOptions =
+  pNodes <|> pNumPoolNodes <|> pure cardanoDefaultTestnetNodesWithOptions
   where
-    defaultSpoOption = NodeOptions []
-
-    mkPoolNodes num = TestnetNodeOptions
-      { optSpoNodes = defaultSpoOption :| L.replicate (num - 1) defaultSpoOption
-      , optRelayNodes = []
-      }
+    pNumPoolNodes :: Parser TestnetNodesWithOptions
+    pNumPoolNodes =
+      (\num -> TestnetNodesWithOptions { optSpoNodes = defaultSpoOption :| L.replicate (num - 1) defaultSpoOption, optRelayNodes = [] }) <$>
+        OA.option ensureAtLeastOne
+          (   OA.long "num-pool-nodes"
+          <>  OA.help "Number of pool nodes. Note this uses a default node configuration for all nodes."
+          <>  OA.metavar "COUNT"
+          )
+    defaultSpoOption = NodeWithOptions Nothing []
 
     ensureAtLeastOne :: OA.ReadM Int
     ensureAtLeastOne = readerAsk >>= \arg ->
@@ -127,6 +130,65 @@ pTestnetNodeOptions =
         Just n | n >= 1 -> pure n
         _ -> fail "Need at least one SPO node to produce blocks, but got none."
 
+    pNodes :: Parser TestnetNodesWithOptions
+    pNodes = OA.option readNodeSpecs
+      (   OA.long "nodes"
+      <>  OA.help "Comma-separated node specifications. SPO nodes must come before relay nodes. \
+                   \Each spec is a role (spo or relay) optionally followed by :node-bin=<path>. \
+                   \If the path contains commas, colons, double quotes, or backslashes, wrap it \
+                   \in double quotes and escape any literal double quotes as \\\" and backslashes \
+                   \as \\\\ within. To prevent bash from consuming the double quotes, enclose the \
+                   \whole argument in single quotes. \
+                   \Examples: --nodes spo,spo:node-bin=/path/to/bin,relay,relay | \
+                   \--nodes 'spo:node-bin=\"/path,with:commas\",relay'"
+      <>  OA.metavar "SPEC[,SPEC...]"
+      )
+
+    readNodeSpecs :: OA.ReadM TestnetNodesWithOptions
+    readNodeSpecs = readerAsk >>= either (fail . show) pure . parseNodeSpecs
+
+-- | Parse a @--nodes@ argument string into 'TestnetNodesWithOptions'.
+parseNodeSpecs :: String -> Either Parsec.ParseError TestnetNodesWithOptions
+parseNodeSpecs = parse (nodeSpecsParser <* eof) "Error parsing node specifications"
+  where
+    nodeSpecsParser :: Parsec.Parsec String () TestnetNodesWithOptions
+    nodeSpecsParser = do
+      specs <- nodeSpec `sepBy1` char ','
+      let (spos, relays) = span (\(role, _) -> role == Spo) specs
+      unless (all (\(role, _) -> role == Relay) relays) $
+        fail "SPO nodes must come before relay nodes. Example: --nodes spo,spo,relay,relay"
+      case map snd spos of
+        [] -> fail "Need at least one SPO node to produce blocks."
+        (s:ss) -> pure $ TestnetNodesWithOptions
+          { optSpoNodes = s :| ss
+          , optRelayNodes = map snd relays
+          }
+
+    nodeSpec :: Parsec.Parsec String () (NodeRole, NodeWithOptions)
+    nodeSpec = do
+      role <- nodeRole
+      bin <- optional $ char ':' *> nodeBinKV
+      pure (role, NodeWithOptions bin [])
+
+    nodeRole :: Parsec.Parsec String () NodeRole
+    nodeRole =
+          Spo <$ try (string "spo" <* notFollowedBy (noneOf ",:\"\\"))
+      <|> Relay <$ try (string "relay" <* notFollowedBy (noneOf ",:\"\\"))
+      <?> "node role (\"spo\" or \"relay\")"
+
+    nodeBinKV :: Parsec.Parsec String () FilePath
+    nodeBinKV = string "node-bin=" *> (quotedPath <|> unquotedPath) <?> "\"node-bin=<path>\", where <path> is the path to the node binary, optionally quoted if it contains special characters"
+
+    quotedPath :: Parsec.Parsec String () FilePath
+    quotedPath = char '"' *> Parsec.many quotedChar <* char '"'
+      where
+        quotedChar = try (char '\\' *> (char '"' <|> char '\\')) <|> noneOf "\""
+
+    unquotedPath :: Parsec.Parsec String () FilePath
+    unquotedPath = many1 (noneOf ",:\"\\")
+
+data NodeRole = Spo | Relay deriving Eq
+
 pOnChainParams :: Parser TestnetOnChainParams
 pOnChainParams = fmap (fromMaybe DefaultParams) <$> optional $
   pCustomParamsFile <|> pMainnetParams
diff --git a/cardano-testnet/src/Parsers/Run.hs b/cardano-testnet/src/Parsers/Run.hs
index 145427db762..1d5971dadac 100644
--- a/cardano-testnet/src/Parsers/Run.hs
+++ b/cardano-testnet/src/Parsers/Run.hs
@@ -91,7 +91,7 @@ runCardanoOptions = \case
     let dirName = envPath fromEnvOptions
     unlessM (doesDirectoryExist dirName) $ error $ "The provided path does not exist or is not a directory: " <> dirName
     conf <- mkConfigAbs dirName
-    nodes <- readNodeOptionsFromEnv (unTmpAbsPath (tempAbsPath conf))
+    nodes <- readNodesWithOptionsFromEnv (unTmpAbsPath (tempAbsPath conf))
     runSimpleApp . runResourceT $ do
       logInfo $ "Starting testnet in environment: " <> display (tempAbsPath conf)
       void $ cardanoTestnet nodes fromEnvRuntimeOptions
diff --git a/cardano-testnet/src/Testnet/Process/RunIO.hs b/cardano-testnet/src/Testnet/Process/RunIO.hs
index 719e2eeb832..fd664db0a64 100644
--- a/cardano-testnet/src/Testnet/Process/RunIO.hs
+++ b/cardano-testnet/src/Testnet/Process/RunIO.hs
@@ -12,6 +12,7 @@ module Testnet.Process.RunIO
   , procNode
   , procKesAgent
   , execKesAgentControl_
+  , procCustom
   , procFlex
   , liftIOAnnotated
   ) where
@@ -144,8 +145,7 @@ execFlexAny' execConfig pkgBin envBin arguments = GHC.withFrozenCallStack $ do
   cp <- procFlex' execConfig pkgBin envBin arguments
   liftIOAnnotated $ IO.readCreateProcessWithExitCode cp ""
 
-
-
+-- | Like 'procFlex', but takes an explicit 'ExecConfig' instead of using 'defaultExecConfig'.
 procFlex'
   :: HasCallStack
   => MonadIO m
@@ -160,7 +160,20 @@ procFlex'
   -- ^ Captured stdout
 procFlex' execConfig pkg binaryEnv arguments = GHC.withFrozenCallStack $ do
   bin <- binFlex pkg binaryEnv
-  return (IO.proc bin arguments)
+  procCustom' execConfig bin arguments
+
+-- | Build a 'CreateProcess' from an already-resolved binary path, arguments, and 'ExecConfig'.
+procCustom'
+  :: (HasCallStack)
+  => MonadIO m
+  => ExecConfig
+  -> FilePath
+  -- ^ Path to the binary
+  -> [String]
+  -- ^ Arguments to the CLI command
+  -> m CreateProcess
+procCustom' execConfig bin arguments = GHC.withFrozenCallStack $
+  pure (IO.proc bin arguments)
     { IO.env = getLast $ execConfigEnv execConfig
     , IO.cwd = getLast $ execConfigCwd execConfig
     -- this allows sending signals to the created processes, without killing the test-suite process
@@ -311,6 +324,17 @@ procFlex
   -- ^ Captured stdout
 procFlex = procFlex' defaultExecConfig
 
+-- | Like 'procFlex', but takes an explicit binary path instead of resolving
+-- via package name and environment variable.
+procCustom
+  :: (HasCallStack)
+  => FilePath
+  -- ^ Path to the binary
+  -> [String]
+  -- ^ Arguments to the CLI command
+  -> RIO env CreateProcess
+procCustom = procCustom' defaultExecConfig
+
 -- This will also catch async exceptions as well.
 liftIOAnnotated :: (HasCallStack, MonadIO m) => IO a -> m a
 liftIOAnnotated action = GHC.withFrozenCallStack $
diff --git a/cardano-testnet/src/Testnet/Runtime.hs b/cardano-testnet/src/Testnet/Runtime.hs
index bd5dbe1527c..e271f264d42 100644
--- a/cardano-testnet/src/Testnet/Runtime.hs
+++ b/cardano-testnet/src/Testnet/Runtime.hs
@@ -57,7 +57,7 @@ import           Cardano.Node.Testnet.Paths (defaultSocketName)
 import qualified Testnet.Ping as Ping
 import           Testnet.Process.Run (ProcessError (..), initiateProcess)
 import           Testnet.Process.RunIO (execCli_, execKesAgentControl_, liftIOAnnotated,
-                   procKesAgent, procNode)
+                   procCustom, procKesAgent, procNode)
 import           Testnet.Types (TestnetKesAgent (..), TestnetNode (..),
                    TestnetRuntime (configurationFile), showIpv4Address, testnetSprockets)
 
@@ -121,11 +121,13 @@ startNode
   -- ^ Node port
   -> Int
   -- ^ Testnet magic
+  -> Maybe FilePath
+  -- ^ Optional custom node binary. 'Nothing' uses the default resolution.
   -> [String]
   -- ^ The command to execute to start the node.
   -- @--socket-path@, @--port@, and @--host-addr@ gets added automatically.
   -> ExceptT NodeStartFailure m TestnetNode
-startNode tp node ipv4 port _testnetMagic nodeCmd = GHC.withFrozenCallStack $ do
+startNode tp node ipv4 port _testnetMagic mNodeBin nodeCmd = GHC.withFrozenCallStack $ do
   let tempBaseAbsPath = makeTmpBaseAbsPath tp
       socketDir = makeSocketDir tp
       logDir = makeLogDir tp
@@ -156,7 +158,10 @@ startNode tp node ipv4 port _testnetMagic nodeCmd = GHC.withFrozenCallStack $ do
                              , "--port", show port
                              , "--host-addr", showIpv4Address ipv4
                              ]
-    nodeProcess <- newExceptT . fmap (first ExecutableRelatedFailure) . try $ runRIO () $ procNode completeNodeCmd
+    nodeProcess <- newExceptT . fmap (first ExecutableRelatedFailure) . try $ runRIO () $
+      case mNodeBin of
+        Nothing -> procNode completeNodeCmd
+        Just bin -> procCustom bin completeNodeCmd
 
     -- The port number if it is obtained using 'H.randomPort', it is firstly bound to and then closed. The closing
     -- and release in the operating system is done asynchronously and can be slow. Here we wait until the port
diff --git a/cardano-testnet/src/Testnet/Start/Cardano.hs b/cardano-testnet/src/Testnet/Start/Cardano.hs
index 0395bd1ba91..e5c89af4e5c 100644
--- a/cardano-testnet/src/Testnet/Start/Cardano.hs
+++ b/cardano-testnet/src/Testnet/Start/Cardano.hs
@@ -17,9 +17,9 @@ module Testnet.Start.Cardano
   , TestnetCreationOptions(..)
   , TestnetRuntimeOptions(..)
   , TestnetEnvOptions(..)
-  , TestnetNodeOptions(..)
-  , NodeOptions(..)
-  , cardanoDefaultTestnetNodeOptions
+  , TestnetNodesWithOptions(..)
+  , NodeWithOptions(..)
+  , cardanoDefaultTestnetNodesWithOptions
 
   , TestnetRuntime (..)
 
@@ -28,7 +28,7 @@ module Testnet.Start.Cardano
   , createTestnetEnv
   , getDefaultAlonzoGenesis
   , getDefaultShelleyGenesis
-  , readNodeOptionsFromEnv
+  , readNodesWithOptionsFromEnv
   , retryOnAddressInUseError
 
   , liftToIntegration
@@ -47,11 +47,14 @@ import           Ouroboros.Network.PeerSelection.RelayAccessPoint (RelayAccessPo
 import           Prelude hiding (lines)
 
 import           Control.Concurrent (threadDelay)
-import           Control.Monad (forM, forM_, unless, when)
+import           Control.Monad (forM, forM_, guard, unless, when)
+import           Control.Monad.Trans.Maybe (runMaybeT)
+import           Control.Exception (IOException)
 import           Control.Monad.Catch
 import           Control.Monad.Trans.Resource (MonadResource, getInternalState)
 import           Data.Aeson
 import qualified Data.Aeson.Encode.Pretty as A
+import qualified Data.Yaml as Yaml
 import qualified Data.ByteString.Lazy as LBS
 import           Data.Default.Class ()
 import           Data.Either
@@ -67,12 +70,13 @@ import           Data.Time.Clock (NominalDiffTime)
 import qualified Data.Time.Clock as DTC
 import           GHC.Stack
 import qualified System.Directory as IO
+import qualified System.Process as Process
 import           System.FilePath ((</>))
 
 import           Testnet.Components.Configuration
 import qualified Testnet.Defaults as Defaults
-import           Cardano.Node.Testnet.Paths (defaultConfigFile, defaultPortFile,
-                   defaultUtxoAddrPath)
+import           Cardano.Node.Testnet.Paths (defaultConfigFile, defaultNodeEnvFile,
+                   defaultPortFile, defaultUtxoAddrPath)
 import           Testnet.Filepath
 import           Testnet.Handlers (interruptNodesOnSigINT)
 import           Testnet.Orphans ()
@@ -93,6 +97,7 @@ import           RIO.State (put)
 import           UnliftIO.Async
 import           UnliftIO.Exception (stringException)
 
+
 liftToIntegration :: HasCallStack => RIO ResourceMap a -> H.Integration a
 liftToIntegration r =  do
    rMap <- lift $ lift getInternalState
@@ -109,7 +114,7 @@ createTestnetEnv :: ()
 createTestnetEnv
   creationOptions@TestnetCreationOptions
     { creationEra=asbe
-    , creationNodes=TestnetNodeOptions{optSpoNodes, optRelayNodes}
+    , creationNodes=TestnetNodesWithOptions{optSpoNodes, optRelayNodes}
     }
   Conf
     { genesisHashesPolicy
@@ -139,8 +144,8 @@ createTestnetEnv
 
   let portNumbersMap = Map.fromList portNumbers
 
-  -- Create network topology and write port files
-  forM_ nodeIds $ \i -> do
+  -- Create network topology, write port files, and write env files for custom binaries
+  forM_ numberedNodes $ \(i, nodeOption) -> do
     let nodeDataDir = tmpAbsPath </> Defaults.defaultNodeDataDir i
     liftIOAnnotated $ IO.createDirectoryIfMissing True nodeDataDir
 
@@ -153,6 +158,14 @@ createTestnetEnv
     let topology = Defaults.defaultP2PTopology producers
     liftIOAnnotated . LBS.writeFile (nodeDataDir </> "topology.json") $ A.encodePretty topology
 
+    -- Write env file for nodes with custom binaries
+    forM_ (nodeBin nodeOption) $ \bin -> do
+        absBin <- liftIOAnnotated $ IO.makeAbsolute bin
+        version <- getNodeVersion absBin
+        let envFile = tmpAbsPath </> defaultNodeEnvFile i
+            nodeEnv = NodeEnv { nodeBinary = absBin, nodeVersion = version }
+        liftIOAnnotated $ Yaml.encodeFile envFile nodeEnv
+
 -- | Starts a number of nodes, as given by the first argument. You can either:
 --
 -- 1. Pass a value 'UserProvidedNodeOptions filepath' to specify your own node configuration file.
@@ -224,12 +237,12 @@ cardanoTestnet
   => MonadResource m
   => MonadCatch m
   => MonadFail m
-  => TestnetNodeOptions -- ^ The nodes to start
+  => TestnetNodesWithOptions -- ^ The nodes to start
   -> TestnetRuntimeOptions -- ^ Runtime options
   -> Conf -- ^ Path to the test sandbox
   -> m TestnetRuntime
 cardanoTestnet
-  TestnetNodeOptions{optSpoNodes=cardanoSpoNodes, optRelayNodes=cardanoRelayNodes}
+  TestnetNodesWithOptions{optSpoNodes=cardanoSpoNodes, optRelayNodes=cardanoRelayNodes}
   TestnetRuntimeOptions
     { runtimeEnableNewEpochStateLogging=enableNewEpochStateLogging
     , runtimeEnableRpc=cardanoEnableRpc
@@ -310,7 +323,7 @@ cardanoTestnet
 
   let portNumbersMap = Map.fromList portNumbers
 
-  eTestnetNodes <- forConcurrently (zip [1..] allNodes) $ \(i, (isSpo, nodeOptions)) -> do
+  eTestnetNodes <- forConcurrently (zip [1..] allNodes) $ \(i, (isSpo, nodeWithOptions)) -> do
     port <- case Map.lookup i portNumbersMap of
       Just p -> pure p
       Nothing -> throwString $ "Port not found for node " <> show i
@@ -318,48 +331,48 @@ cardanoTestnet
         nodeDataDir = tmpAbsPath </> Defaults.defaultNodeDataDir i
         nodePoolKeysDir = tmpAbsPath </> Defaults.defaultSpoKeysDir i
     (mKeys, spoNodeCliArgs) <- if not isSpo then pure (Nothing, []) else do
-          -- depending on testnet configuration, either start a 'kes-agent' or use a key from disk
-          kesSourceCliArg <-
-            case cardanoKESSource of
-              UseKesKeyFile -> pure ["--shelley-kes-key", nodePoolKeysDir </> "kes.skey"]
-              UseKesSocket -> do
-                -- wait startTimeOffsetSeconds so that the startTime from shelly-genesis.json is not in the future,
-                -- as otherwise we will trigger an underflow in kes-agent with a negative time difference.
-                liftIOAnnotated $ threadDelay (startTimeOffsetSeconds * 1_000_000)
-                kesAgent <- runExceptT $
-                  initAndStartKesAgent (TmpAbsolutePath tmpAbsPath) nodeName
-                    TestnetKesAgentArgs{ tkaaShelleyGenesisFile = shelleyGenesisFile
-                                       , tkaaColdVKeyFile = nodePoolKeysDir </> "cold.vkey"
-                                       , tkaaColdSKeyFile = nodePoolKeysDir </> "cold.skey"
-                                       , tkaaKesVKeyFile = nodePoolKeysDir </> "kes.vkey"
-                                       , tkaaOpcertCounterFile = nodePoolKeysDir </> "opcert.counter"
-                                       , tkaaOpcertFile = nodePoolKeysDir </> "opcert.cert"
-                                       }
-                case kesAgent of
-                  Left e -> do
-                    -- TODO: fail if could not start KES agent
-                    liftIOAnnotated . putStrLn $ "Could not start KES agent: " <> show e
-                    pure ["--shelley-kes-key", nodePoolKeysDir </> "kes.skey"]
-                  Right (TestnetKesAgent{kesAgentServiceSprocket}) ->
-                    pure ["--shelley-kes-agent-socket", sprocketSystemName kesAgentServiceSprocket]
-          let shelleyCliArgs = [ "--shelley-vrf-key", unFile $ signingKey poolNodeKeysVrf
-                               , "--shelley-operational-certificate", nodePoolKeysDir </> "opcert.cert"
-                               ]
-              byronCliArgs = [ "--byron-delegation-certificate", nodePoolKeysDir </> "byron-delegation.cert"
-                             , "--byron-signing-key", nodePoolKeysDir </> "byron-delegate.key"
-                             ]
-              keys@SpoNodeKeys{poolNodeKeysVrf} = mkTestnetNodeKeyPaths i
-          pure (Just keys, kesSourceCliArg <> shelleyCliArgs <> byronCliArgs)
+      -- depending on testnet configuration, either start a 'kes-agent' or use a key from disk
+      kesSourceCliArg <-
+        case cardanoKESSource of
+          UseKesKeyFile -> pure ["--shelley-kes-key", nodePoolKeysDir </> "kes.skey"]
+          UseKesSocket -> do
+            -- wait startTimeOffsetSeconds so that the startTime from shelly-genesis.json is not in the future,
+            -- as otherwise we will trigger an underflow in kes-agent with a negative time difference.
+            liftIOAnnotated $ threadDelay (startTimeOffsetSeconds * 1_000_000)
+            kesAgent <- runExceptT $
+              initAndStartKesAgent (TmpAbsolutePath tmpAbsPath) nodeName
+                TestnetKesAgentArgs{ tkaaShelleyGenesisFile = shelleyGenesisFile
+                                   , tkaaColdVKeyFile = nodePoolKeysDir </> "cold.vkey"
+                                   , tkaaColdSKeyFile = nodePoolKeysDir </> "cold.skey"
+                                   , tkaaKesVKeyFile = nodePoolKeysDir </> "kes.vkey"
+                                   , tkaaOpcertCounterFile = nodePoolKeysDir </> "opcert.counter"
+                                   , tkaaOpcertFile = nodePoolKeysDir </> "opcert.cert"
+                                   }
+            case kesAgent of
+              Left e -> do
+                -- TODO: fail if could not start KES agent
+                liftIOAnnotated . putStrLn $ "Could not start KES agent: " <> show e
+                pure ["--shelley-kes-key", nodePoolKeysDir </> "kes.skey"]
+              Right (TestnetKesAgent{kesAgentServiceSprocket}) ->
+                pure ["--shelley-kes-agent-socket", sprocketSystemName kesAgentServiceSprocket]
+      let shelleyCliArgs = [ "--shelley-vrf-key", unFile $ signingKey poolNodeKeysVrf
+                           , "--shelley-operational-certificate", nodePoolKeysDir </> "opcert.cert"
+                           ]
+          byronCliArgs = [ "--byron-delegation-certificate", nodePoolKeysDir </> "byron-delegation.cert"
+                         , "--byron-signing-key", nodePoolKeysDir </> "byron-delegate.key"
+                         ]
+          keys@SpoNodeKeys{poolNodeKeysVrf} = mkTestnetNodeKeyPaths i
+      pure (Just keys, kesSourceCliArg <> shelleyCliArgs <> byronCliArgs)
 
     eRuntime <- runExceptT . retryOnAddressInUseError $
-      startNode (TmpAbsolutePath tmpAbsPath) nodeName testnetDefaultIpv4Address port testnetMagic $
+      startNode (TmpAbsolutePath tmpAbsPath) nodeName testnetDefaultIpv4Address port testnetMagic (nodeBin nodeWithOptions) $
         [ "run"
         , "--config", nodeConfigFile
         , "--topology", nodeDataDir </> "topology.json"
         , "--database-path", nodeDataDir </> "db"
         ]
         <> spoNodeCliArgs
-        <> nodeExtraCliArgs nodeOptions
+        <> nodeExtraCliArgs nodeWithOptions
         <> ["--grpc-enable" | RpcEnabled <- [cardanoEnableRpc]]
     pure $ eRuntime <&> \rt -> rt{poolKeys=mKeys}
 
@@ -501,8 +514,8 @@ retryOnAddressInUseError act = withFrozenCallStack $ go maximumTimeout retryTime
 -- and checks @pools-keys/@ to classify each as SPO or relay.
 -- Validates that nodes are consecutively numbered starting from 1,
 -- and that all SPO nodes come before relay nodes.
-readNodeOptionsFromEnv :: HasCallStack => MonadIO m => FilePath -> m TestnetNodeOptions
-readNodeOptionsFromEnv envDir = do
+readNodesWithOptionsFromEnv :: HasCallStack => MonadIO m => FilePath -> m TestnetNodesWithOptions
+readNodesWithOptionsFromEnv envDir = do
   entries <- liftIO $ IO.listDirectory (envDir </> "node-data")
   let nodeNums = sort $ mapMaybe parseNodeNum entries
   when (null nodeNums) $
@@ -517,12 +530,48 @@ readNodeOptionsFromEnv envDir = do
   when (null spoFlags) $
     throwString "No SPO node directories found in environment"
   let nSpos = length spoFlags
-  let spoOpts = map (const (NodeOptions [])) [1 .. nSpos]
-      relayOpts = map (const (NodeOptions [])) [nSpos + 1 .. length nodeNums]
+  spoOpts <- mapM readNodeOpt [1 .. nSpos]
+  relayOpts <- mapM readNodeOpt [nSpos + 1 .. length nodeNums]
   case spoOpts of
-    (s:ss) -> pure $ TestnetNodeOptions { optSpoNodes = s :| ss, optRelayNodes = relayOpts }
+    (s:ss) -> pure $ TestnetNodesWithOptions { optSpoNodes = s :| ss, optRelayNodes = relayOpts }
     [] -> throwString "No SPO node directories found in environment"
   where
     parseNodeNum s = do
       rest <- stripPrefix "node" s
       readMaybe rest :: Maybe Int
+    readNodeOpt i = do
+      bin <- readNodeBinFromEnvFile (envDir </> defaultNodeEnvFile i)
+      pure $ NodeWithOptions bin []
+
+data NodeEnv = NodeEnv
+  { nodeBinary :: FilePath
+  , nodeVersion :: String
+  } deriving (Eq, Show)
+
+instance FromJSON NodeEnv where
+  parseJSON = withObject "NodeEnv" $ \o ->
+    NodeEnv <$> o .: "node_binary"
+            <*> o .: "node_version"
+
+instance ToJSON NodeEnv where
+  toJSON NodeEnv{nodeBinary, nodeVersion} =
+    object [ "node_binary" .= nodeBinary
+           , "node_version" .= nodeVersion
+           ]
+
+readNodeBinFromEnvFile :: (HasCallStack, MonadIO m) => FilePath -> m (Maybe FilePath)
+readNodeBinFromEnvFile envFile = runMaybeT $ do
+  guard =<< liftIOAnnotated (IO.doesFileExist envFile)
+  NodeEnv{nodeBinary} <- either failParse pure =<< liftIOAnnotated (Yaml.decodeFileEither envFile)
+  pure nodeBinary
+  where
+    failParse err = throwString $ "Failed to parse node env file " <> envFile <> ": " <> show err
+
+getNodeVersion :: HasCallStack => MonadIO m => FilePath -> m String
+getNodeVersion bin = liftIOAnnotated $ do
+  output <- Process.readProcess bin ["--version"] ""
+    `catch` \(e :: IOException) ->
+      throwString $ "Failed to run " <> bin <> " --version: " <> displayException e
+  case words output of
+    ("cardano-node":version:_) -> pure version
+    _ -> throwString $ "Unexpected output from " <> bin <> " --version (expected 'cardano-node <version> ...'): " <> output
diff --git a/cardano-testnet/src/Testnet/Start/Types.hs b/cardano-testnet/src/Testnet/Start/Types.hs
index c221f451480..c53ce344d9c 100644
--- a/cardano-testnet/src/Testnet/Start/Types.hs
+++ b/cardano-testnet/src/Testnet/Start/Types.hs
@@ -31,9 +31,9 @@ module Testnet.Start.Types
   , UpdateTimestamps(..)
   , TestnetOnChainParams(..)
   , mainnetParamsRequest
-  , TestnetNodeOptions(..)
-  , NodeOptions(..)
-  , cardanoDefaultTestnetNodeOptions
+  , TestnetNodesWithOptions(..)
+  , NodeWithOptions(..)
+  , cardanoDefaultTestnetNodesWithOptions
   , GenesisOptions(..)
   , UserProvidedData(..)
   , UserProvidedGeneses(..)
@@ -176,7 +176,7 @@ data RpcSupport
 -- 'Testnet.Start.Cardano.createAndRunTestnet' in tests.
 data TestnetCreationOptions = TestnetCreationOptions
   { -- | Options controlling how many nodes to create and of which type.
-    creationNodes :: TestnetNodeOptions
+    creationNodes :: TestnetNodesWithOptions
   , creationEra :: AnyShelleyBasedEra -- ^ The era to start at
   , creationMaxSupply :: Word64 -- ^ The amount of Lovelace you are starting your testnet with (forwarded to shelley genesis)
                                 -- TODO move me to GenesisOptions when https://github.com/IntersectMBO/cardano-cli/pull/874 makes it to cardano-node
@@ -187,7 +187,7 @@ data TestnetCreationOptions = TestnetCreationOptions
 
 instance Default TestnetCreationOptions where
   def = TestnetCreationOptions
-    { creationNodes = cardanoDefaultTestnetNodeOptions
+    { creationNodes = cardanoDefaultTestnetNodesWithOptions
     , creationEra = AnyShelleyBasedEra ShelleyBasedEraConway
     , creationMaxSupply = 100_000_020_000_000
     , creationNumDReps = 3
@@ -259,15 +259,16 @@ instance Default GenesisOptions where
     }
 
 -- | Configuration specific to each node
-newtype NodeOptions = NodeOptions
-  { nodeExtraCliArgs :: [String] -- ^ Extra CLI arguments passed to @cardano-node run@
+data NodeWithOptions = NodeWithOptions
+  { nodeBin :: Maybe FilePath -- ^ Path to the @cardano-node@ binary to use for running this node. 'Nothing' uses the default resolution mechanism.
+  , nodeExtraCliArgs :: [String] -- ^ Extra CLI arguments passed to @cardano-node run@
   } deriving (Eq, Show)
 
 -- | Specifies the nodes to create for the testnet, split by role (SPO and relay).
 -- SPO nodes participate in block production. Relay nodes only forward blocks.
-data TestnetNodeOptions = TestnetNodeOptions
-  { optSpoNodes :: NonEmpty NodeOptions -- ^ SPO (stake pool operator) nodes. Must have at least one.
-  , optRelayNodes :: [NodeOptions] -- ^ Relay (non-producing) nodes
+data TestnetNodesWithOptions = TestnetNodesWithOptions
+  { optSpoNodes :: NonEmpty NodeWithOptions -- ^ SPO (stake pool operator) nodes. Must have at least one.
+  , optRelayNodes :: [NodeWithOptions] -- ^ Relay (non-producing) nodes
   } deriving (Eq, Show)
 
 -- | Type used to track whether the user is providing its data (node configuration file path, genesis file, etc.)
@@ -280,11 +281,11 @@ data UserProvidedData a =
 instance Default (UserProvidedData a) where
   def = NoUserProvidedData
 
-cardanoDefaultTestnetNodeOptions :: TestnetNodeOptions
-cardanoDefaultTestnetNodeOptions = TestnetNodeOptions
-  { optSpoNodes = NodeOptions [] :| []
-  , optRelayNodes = [ NodeOptions []
-                    , NodeOptions []
+cardanoDefaultTestnetNodesWithOptions :: TestnetNodesWithOptions
+cardanoDefaultTestnetNodesWithOptions = TestnetNodesWithOptions
+  { optSpoNodes = NodeWithOptions Nothing [] :| []
+  , optRelayNodes = [ NodeWithOptions Nothing []
+                    , NodeWithOptions Nothing []
                     ]
   }
 
diff --git a/cardano-testnet/test/cardano-testnet-golden/files/golden/help.cli b/cardano-testnet/test/cardano-testnet-golden/files/golden/help.cli
index 3338b742378..727d84e5bb3 100644
--- a/cardano-testnet/test/cardano-testnet-golden/files/golden/help.cli
+++ b/cardano-testnet/test/cardano-testnet-golden/files/golden/help.cli
@@ -2,7 +2,7 @@ Usage: cardano-testnet (cardano | create-env | version | help)
 
 Usage: cardano-testnet cardano 
   [ --node-env FILEPATH [--preserve-timestamps]
-  | [--num-pool-nodes COUNT]
+  | [--nodes SPEC[,SPEC...] | --num-pool-nodes COUNT]
     [--max-lovelace-supply WORD64]
     [--num-dreps NUMBER]
     [--testnet-magic INT]
@@ -18,7 +18,8 @@ Usage: cardano-testnet cardano
 
   Start a testnet and keep it running until stopped
 
-Usage: cardano-testnet create-env [--num-pool-nodes COUNT]
+Usage: cardano-testnet create-env 
+  [--nodes SPEC[,SPEC...] | --num-pool-nodes COUNT]
   [--max-lovelace-supply WORD64]
   [--num-dreps NUMBER]
   [--testnet-magic INT]
diff --git a/cardano-testnet/test/cardano-testnet-golden/files/golden/help/cardano.cli b/cardano-testnet/test/cardano-testnet-golden/files/golden/help/cardano.cli
index af2f574cdec..cad989c099a 100644
--- a/cardano-testnet/test/cardano-testnet-golden/files/golden/help/cardano.cli
+++ b/cardano-testnet/test/cardano-testnet-golden/files/golden/help/cardano.cli
@@ -1,6 +1,6 @@
 Usage: cardano-testnet cardano 
   [ --node-env FILEPATH [--preserve-timestamps]
-  | [--num-pool-nodes COUNT]
+  | [--nodes SPEC[,SPEC...] | --num-pool-nodes COUNT]
     [--max-lovelace-supply WORD64]
     [--num-dreps NUMBER]
     [--testnet-magic INT]
@@ -23,6 +23,17 @@ Available options:
                            pass it with this argument.
   --preserve-timestamps    Do not update the time stamps in genesis files to
                            current date.
+  --nodes SPEC[,SPEC...]   Comma-separated node specifications. SPO nodes must
+                           come before relay nodes. Each spec is a role (spo or
+                           relay) optionally followed by :node-bin=<path>. If
+                           the path contains commas, colons, double quotes, or
+                           backslashes, wrap it in double quotes and escape any
+                           literal double quotes as \" and backslashes as \\
+                           within. To prevent bash from consuming the double
+                           quotes, enclose the whole argument in single quotes.
+                           Examples: --nodes
+                           spo,spo:node-bin=/path/to/bin,relay,relay | --nodes
+                           'spo:node-bin="/path,with:commas",relay'
   --num-pool-nodes COUNT   Number of pool nodes. Note this uses a default node
                            configuration for all nodes.
   --max-lovelace-supply WORD64
diff --git a/cardano-testnet/test/cardano-testnet-golden/files/golden/help/create-env.cli b/cardano-testnet/test/cardano-testnet-golden/files/golden/help/create-env.cli
index 20d7b4405c6..27776f085e5 100644
--- a/cardano-testnet/test/cardano-testnet-golden/files/golden/help/create-env.cli
+++ b/cardano-testnet/test/cardano-testnet-golden/files/golden/help/create-env.cli
@@ -1,4 +1,5 @@
-Usage: cardano-testnet create-env [--num-pool-nodes COUNT]
+Usage: cardano-testnet create-env 
+  [--nodes SPEC[,SPEC...] | --num-pool-nodes COUNT]
   [--max-lovelace-supply WORD64]
   [--num-dreps NUMBER]
   [--testnet-magic INT]
@@ -11,6 +12,17 @@ Usage: cardano-testnet create-env [--num-pool-nodes COUNT]
   Create a sandbox for Cardano testnet
 
 Available options:
+  --nodes SPEC[,SPEC...]   Comma-separated node specifications. SPO nodes must
+                           come before relay nodes. Each spec is a role (spo or
+                           relay) optionally followed by :node-bin=<path>. If
+                           the path contains commas, colons, double quotes, or
+                           backslashes, wrap it in double quotes and escape any
+                           literal double quotes as \" and backslashes as \\
+                           within. To prevent bash from consuming the double
+                           quotes, enclose the whole argument in single quotes.
+                           Examples: --nodes
+                           spo,spo:node-bin=/path/to/bin,relay,relay | --nodes
+                           'spo:node-bin="/path,with:commas",relay'
   --num-pool-nodes COUNT   Number of pool nodes. Note this uses a default node
                            configuration for all nodes.
   --max-lovelace-supply WORD64
diff --git a/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Cli/KesPeriodInfo.hs b/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Cli/KesPeriodInfo.hs
index bb8f062593b..fb3db527b5d 100644
--- a/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Cli/KesPeriodInfo.hs
+++ b/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Cli/KesPeriodInfo.hs
@@ -262,7 +262,7 @@ hprop_kes_period_info = integrationRetryWorkspace 2 "kes-period-info" $ \tempAbs
   H.lbsWriteFile (unFile configurationFile) jsonBS
   newNodePortNumber <- H.randomPort testnetDefaultIpv4Address
   eRuntime <- runExceptT . retryOnAddressInUseError $
-    startNode tempAbsPath "test-spo" testnetDefaultIpv4Address newNodePortNumber testnetMagic
+    startNode tempAbsPath "test-spo" testnetDefaultIpv4Address newNodePortNumber testnetMagic Nothing
         [ "run"
         , "--config", unFile configurationFile
         , "--topology", topologyFile
diff --git a/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Cli/LeadershipSchedule.hs b/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Cli/LeadershipSchedule.hs
index 91e98ad35ea..176c464ca71 100644
--- a/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Cli/LeadershipSchedule.hs
+++ b/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Cli/LeadershipSchedule.hs
@@ -71,10 +71,10 @@ hprop_leadershipSchedule = integrationRetryWorkspace 2 "leadership-schedule" $ \
       cTestnetOptions = def
         { creationEra = asbe
         , creationNodes =
-            TestnetNodeOptions
-              { optSpoNodes = NodeOptions [] :|
-                [ NodeOptions []
-                , NodeOptions []
+            TestnetNodesWithOptions
+              { optSpoNodes = NodeWithOptions Nothing [] :|
+                [ NodeWithOptions Nothing []
+                , NodeWithOptions Nothing []
                 ]
               , optRelayNodes = []
               }
@@ -267,7 +267,7 @@ hprop_leadershipSchedule = integrationRetryWorkspace 2 "leadership-schedule" $ \
   H.lbsWriteFile (unFile configurationFile) jsonBS
   newNodePort <- H.randomPort testnetDefaultIpv4Address
   eRuntime <- runExceptT . retryOnAddressInUseError $
-    startNode (TmpAbsolutePath work) "test-spo" testnetDefaultIpv4Address newNodePort testnetMagic
+    startNode (TmpAbsolutePath work) "test-spo" testnetDefaultIpv4Address newNodePort testnetMagic Nothing
         [ "run"
         , "--config", unFile configurationFile
         , "--topology", topologyFile
diff --git a/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Gov/ProposeNewConstitutionSPO.hs b/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Gov/ProposeNewConstitutionSPO.hs
index 5e810cb287a..7add69da333 100644
--- a/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Gov/ProposeNewConstitutionSPO.hs
+++ b/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Gov/ProposeNewConstitutionSPO.hs
@@ -59,10 +59,10 @@ hprop_ledger_events_propose_new_constitution_spo = integrationRetryWorkspace 2 "
       creationOptions = def
         { creationEra = AnyShelleyBasedEra sbe
         , creationNodes =
-            TestnetNodeOptions
-              { optSpoNodes = NodeOptions [] :|
-                [ NodeOptions []
-                , NodeOptions []
+            TestnetNodesWithOptions
+              { optSpoNodes = NodeWithOptions Nothing [] :|
+                [ NodeWithOptions Nothing []
+                , NodeWithOptions Nothing []
                 ]
               , optRelayNodes = []
               }
diff --git a/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Node/Shutdown.hs b/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Node/Shutdown.hs
index 00408cfcdeb..4e19f302e6e 100644
--- a/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Node/Shutdown.hs
+++ b/cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Node/Shutdown.hs
@@ -208,8 +208,8 @@ hprop_shutdownOnSlotSynced = integrationRetryWorkspace 2 "shutdown-on-slot-synce
       slotLen = 0.1
   let creationOptions = def
         { creationNodes =
-            TestnetNodeOptions
-              { optSpoNodes = NodeOptions ["--shutdown-on-slot-synced", show maxSlot] :| []
+            TestnetNodesWithOptions
+              { optSpoNodes = NodeWithOptions Nothing ["--shutdown-on-slot-synced", show maxSlot] :| []
               , optRelayNodes = []
               }
         , creationGenesisOptions = def