diff --git a/src/flexmeasures_client/s2/__init__.py b/src/flexmeasures_client/s2/__init__.py
index 02b50e87..981269e1 100644
--- a/src/flexmeasures_client/s2/__init__.py
+++ b/src/flexmeasures_client/s2/__init__.py
@@ -7,9 +7,9 @@
 from dataclasses import dataclass
 from datetime import datetime
 from typing import Callable, Coroutine, Dict, Type
+from zoneinfo import ZoneInfo
 
 import pydantic
-import pytz
 
 try:
     from s2python.common import ReceptionStatus, ReceptionStatusValues, RevokeObject
@@ -125,7 +125,7 @@ def __init__(self, max_size: int = 100, timezone: str = "UTC") -> None:
 
         self.outgoing_messages_status = SizeLimitOrderedDict(max_size=max_size)
 
-        self._timezone = pytz.timezone(timezone)
+        self._timezone = ZoneInfo(timezone)
 
         self.discover()
 
diff --git a/src/flexmeasures_client/s2/control_types/FRBC/frbc_simple.py b/src/flexmeasures_client/s2/control_types/FRBC/frbc_simple.py
index 6e81f291..698b8126 100644
--- a/src/flexmeasures_client/s2/control_types/FRBC/frbc_simple.py
+++ b/src/flexmeasures_client/s2/control_types/FRBC/frbc_simple.py
@@ -4,8 +4,7 @@
 """
 
 from datetime import datetime, timedelta
-
-import pytz
+from zoneinfo import ZoneInfo
 
 try:
     from s2python.frbc import (
@@ -52,14 +51,14 @@ def __init__(
         self._schedule_duration = schedule_duration
         self._soc_sensor_id = soc_sensor_id
         self._rm_discharge_sensor_id = rm_discharge_sensor_id
-        self._timezone = pytz.timezone(timezone)
+        self._timezone = ZoneInfo(timezone)
 
         # delay the start of the schedule from the time `valid_from`
         # of the FRBC.SystemDescription.
         self._valid_from_shift = valid_from_shift
 
     def now(self):
-        return self._timezone.localize(datetime.now())
+        return datetime.now(self._timezone)
 
     async def send_storage_status(self, status: FRBCStorageStatus):
         await self._fm_client.post_measurements(
diff --git a/src/flexmeasures_client/s2/control_types/FRBC/frbc_tunes.py b/src/flexmeasures_client/s2/control_types/FRBC/frbc_tunes.py
index 6b822791..e2496182 100644
--- a/src/flexmeasures_client/s2/control_types/FRBC/frbc_tunes.py
+++ b/src/flexmeasures_client/s2/control_types/FRBC/frbc_tunes.py
@@ -8,6 +8,7 @@
 import json
 import math
 from datetime import datetime, timedelta
+from zoneinfo import ZoneInfo
 
 import pandas as pd
 from requests.exceptions import HTTPError
@@ -25,7 +26,6 @@
 from typing import cast
 
 import pydantic
-import pytz
 
 try:
     from s2python.common import (
@@ -153,7 +153,7 @@ def __init__(
         self._consumption_price_sensor_id = consumption_price_sensor
         self._production_price_sensor_id = production_price_sensor
 
-        self._timezone = pytz.timezone(timezone)
+        self._timezone = ZoneInfo(timezone)
 
         # delay the start of the schedule from the time `valid_from` of the FRBC.SystemDescription
         self._valid_from_shift = valid_from_shift
diff --git a/src/flexmeasures_client/s2/script/websockets_client.py b/src/flexmeasures_client/s2/script/websockets_client.py
index bf990c7b..c52910a3 100644
--- a/src/flexmeasures_client/s2/script/websockets_client.py
+++ b/src/flexmeasures_client/s2/script/websockets_client.py
@@ -1,8 +1,8 @@
 import asyncio
 from datetime import datetime
+from zoneinfo import ZoneInfo
 
 import aiohttp
-import pytz
 from s2python.common import (
     Commodity,
     CommodityQuantity,
@@ -139,9 +139,7 @@ async def main_s2():
                 fill_level_range=NumberRange(start_of_range=0.05, end_of_range=0.45),
             )
 
-            valid_from = pytz.timezone("Europe/Amsterdam").localize(
-                datetime(2026, 1, 15, 20)
-            )
+            valid_from = datetime(2026, 1, 15, 20, tzinfo=ZoneInfo("Europe/Amsterdam"))
 
             system_description_message = FRBCSystemDescription(
                 message_id=get_unique_id(),
diff --git a/tests/s2/test_timezone.py b/tests/s2/test_timezone.py
new file mode 100644
index 00000000..59ab27b6
--- /dev/null
+++ b/tests/s2/test_timezone.py
@@ -0,0 +1,22 @@
+from zoneinfo import ZoneInfo
+
+from flexmeasures_client.s2 import Handler
+from flexmeasures_client.s2.control_types.FRBC.frbc_simple import FRBCSimple
+
+
+def test_handler_uses_zoneinfo_timezone():
+    handler = Handler(timezone="Europe/Amsterdam")
+
+    assert handler.now().tzinfo == ZoneInfo("Europe/Amsterdam")
+
+
+def test_frbc_simple_now_uses_zoneinfo_timezone():
+    frbc = FRBCSimple(
+        power_sensor_id=1,
+        soc_sensor_id=2,
+        rm_discharge_sensor_id=3,
+        price_sensor_id=4,
+        timezone="Europe/Amsterdam",
+    )
+
+    assert frbc.now().tzinfo == ZoneInfo("Europe/Amsterdam")