diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index a23b1919..7336bc4a 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -30,6 +30,7 @@ jobs:
         python_version:
           - "3.9"
           - "3.10"
+          - "3.11"
 
     steps:
       - name: Check Out VCS Repository
@@ -85,6 +86,7 @@ jobs:
         python_version:
           - "3.9"
           - "3.10"
+          - "3.11"
 
     steps:
       - name: Check Out VCS Repository
diff --git a/.github/workflows/deploy.yaml b/.github/workflows/deploy.yaml
index 97db5c26..eb910aba 100644
--- a/.github/workflows/deploy.yaml
+++ b/.github/workflows/deploy.yaml
@@ -44,7 +44,7 @@ jobs:
         id: set_up_python
         uses: actions/setup-python@v6.0.0
         with:
-          python-version: "3.10"
+          python-version: "3.11"
 
       - name: Restoring/Saving Cache
         uses: actions/cache@v4.3.0
diff --git a/.github/workflows/release.yaml b/.github/workflows/release.yaml
index a180543a..f2225d7e 100644
--- a/.github/workflows/release.yaml
+++ b/.github/workflows/release.yaml
@@ -41,7 +41,7 @@ jobs:
         id: set_up_python
         uses: actions/setup-python@v6.0.0
         with:
-          python-version: "3.10"
+          python-version: "3.11"
 
       - name: Create Python Virtual Environment
         run: make python-virtualenv PYTHON_VIRTUALENV_DIR="venv"
diff --git a/README.md b/README.md
index d44ee39f..200744ad 100644
--- a/README.md
+++ b/README.md
@@ -31,7 +31,7 @@ The full documentation is at <https://lib-cl-sii-python.readthedocs.io>.
 
 ## Supported Python versions
 
-Only Python 3.9 and 3.10. Python 3.8 and below will not work because we use some features
+Only Python 3.9, 3.10, and 3.11. Python 3.8 and below will not work because we use some features
 introduced in Python 3.9.
 
 ## Quickstart
diff --git a/pyproject.toml b/pyproject.toml
index e6b64ecb..90e7ad24 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -28,7 +28,7 @@ dependencies = [
   "signxml>=4.0.0",
   "typing-extensions>=4.0.1",
 ]
-requires-python = ">=3.9, <3.11"
+requires-python = ">=3.9, <3.12"
 authors = [
   {name = "Fyntex TI SpA", email = "no-reply@fyntex.ai"},
 ]
@@ -44,6 +44,7 @@ classifiers = [
   "Programming Language :: Python :: 3",
   "Programming Language :: Python :: 3.9",
   "Programming Language :: Python :: 3.10",
+  "Programming Language :: Python :: 3.11",
 ]
 dynamic = ["version"]
 
diff --git a/src/tests/test_libs_tz_utils.py b/src/tests/test_libs_tz_utils.py
index a86c6710..af24c497 100644
--- a/src/tests/test_libs_tz_utils.py
+++ b/src/tests/test_libs_tz_utils.py
@@ -1,5 +1,6 @@
 import datetime
 import re
+import sys
 import unittest
 
 from cl_sii.libs.tz_utils import (  # noqa: F401
@@ -74,7 +75,12 @@ def test_validate_dt_tz_tzinfo_zone_attribute_check(self) -> None:
         )
         with self.assertRaisesRegex(AssertionError, expected_error_message):
             validate_dt_tz(dt_with_tzinfo_utc_pytz, tzinfo_utc_stdlib)
-        expected_error_message = re.compile(r"^Object UTC must have 'zone' attribute.$")
+        if sys.version_info >= (3, 11):
+            expected_error_message = re.compile(
+                r"^Object datetime.timezone.utc must have 'zone' attribute.$"
+            )
+        else:
+            expected_error_message = re.compile(r"^Object UTC must have 'zone' attribute.$")
         with self.assertRaisesRegex(AssertionError, expected_error_message):
             validate_dt_tz(dt_with_tzinfo_utc_stdlib, tzinfo_utc_pytz)
 
@@ -86,8 +92,15 @@ def test_validate_dt_tz_tzinfo_zone_attribute_check(self) -> None:
         )
         with self.assertRaisesRegex(AssertionError, expected_error_message):
             validate_dt_tz(dt_with_tzinfo_not_utc_pytz, tzinfo_not_utc_stdlib)  # type: ignore
-        expected_error_message = re.compile(
-            r"^Object" r" UTC-03:00" r" must have 'zone' attribute.$"
-        )
+        if sys.version_info >= (3, 11):
+            expected_error_message = re.compile(
+                r"^Object"
+                r" datetime.timezone\(datetime.timedelta\(days=-1, seconds=75600\)\)"
+                r" must have 'zone' attribute.$"
+            )
+        else:
+            expected_error_message = re.compile(
+                r"^Object" r" UTC-03:00" r" must have 'zone' attribute.$"
+            )
         with self.assertRaisesRegex(AssertionError, expected_error_message):
             validate_dt_tz(dt_with_tzinfo_not_utc_stdlib, tzinfo_not_utc_pytz)
diff --git a/tox.ini b/tox.ini
index c62778c7..cfeac9c0 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,6 +2,7 @@
 envlist =
     py39,
     py310,
+    py311,
 
 [testenv]
 setenv =
@@ -13,3 +14,4 @@ deps =
 basepython =
     py39: python3.9
     py310: python3.10
+    py311: python3.11