diff --git a/docs/source/advanced-configuration.rst b/docs/source/advanced-configuration.rst
index a3cd8c1..b62cd84 100644
--- a/docs/source/advanced-configuration.rst
+++ b/docs/source/advanced-configuration.rst
@@ -139,6 +139,20 @@ To exclude a set of pages, add each page's path to ``sitemap_exclude``:
        "genindex.html",
    ]
 
+.. _configuration_lastmod:
+
+Adding Last Modification Date
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+To add the date of the last page modification set ``sitemap_lastmod`` a string
+representing the last modification date.
+
+.. code-block:: python
+
+   sitemap_lastmod = "2024-08-13"
+   # or
+   import datetime
+   sitemap_lastmod = f"{datetime.datetime.now():%Y-%m-%d}"
 
 .. _sitemapindex.xml: https://support.google.com/webmasters/answer/75712?hl=en
 .. _sitemaps.org: https://www.sitemaps.org/protocol.html
diff --git a/docs/source/conf.py b/docs/source/conf.py
index 29ae58f..993eaea 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -11,6 +11,7 @@
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
 #
+import datetime
 import re
 import subprocess
 
@@ -121,6 +122,8 @@
 # Output file base name for HTML help builder.
 htmlhelp_basename = "SphinxSitemapdoc"
 
+# Set last modification date in sitemap
+sitemap_lastmod = f"{datetime.datetime.now():%Y-%m-%d}"
 
 # -- Options for LaTeX output ------------------------------------------------
 
diff --git a/docs/source/configuration-values.rst b/docs/source/configuration-values.rst
index 3cf4be7..3294cfc 100644
--- a/docs/source/configuration-values.rst
+++ b/docs/source/configuration-values.rst
@@ -34,3 +34,11 @@ A list of of possible configuration values to configure in **conf.py**:
    See :ref:`configuration_excluding_pages` for more information.
 
    .. versionadded:: 2.6.0
+
+.. confval:: sitemap_lastmod
+
+   The entry ``lastmod`` is added to the output file.
+
+   See :ref:`configuration_lastmod` for more information.
+
+   .. versionadded:: 2.7.0
diff --git a/sphinx_sitemap/__init__.py b/sphinx_sitemap/__init__.py
index 7779093..116d5bb 100644
--- a/sphinx_sitemap/__init__.py
+++ b/sphinx_sitemap/__init__.py
@@ -21,7 +21,7 @@
 from sphinx.application import Sphinx
 from sphinx.util.logging import getLogger
 
-__version__ = "2.6.0"
+__version__ = "2.7.0"
 
 logger = getLogger(__name__)
 
@@ -44,6 +44,8 @@ def setup(app: Sphinx) -> Dict[str, Any]:
 
     app.add_config_value("sitemap_excludes", default=[], rebuild="")
 
+    app.add_config_value("sitemap_lastmod", default=None, rebuild="", types=[str])
+
     try:
         app.add_config_value("html_baseurl", default=None, rebuild="")
     except BaseException:
@@ -203,6 +205,10 @@ def create_sitemap(app: Sphinx, exception):
         ElementTree.SubElement(url, "loc").text = site_url + scheme.format(
             lang=lang, version=version, link=link
         )
+        if app.builder.config.sitemap_lastmod is not None:
+            ElementTree.SubElement(url, "lastmod").text = (
+                app.builder.config.sitemap_lastmod
+            )
 
         for lang in locales:
             lang = lang + "/"
diff --git a/tests/test_simple.py b/tests/test_simple.py
index a27f4d2..4848fab 100644
--- a/tests/test_simple.py
+++ b/tests/test_simple.py
@@ -68,12 +68,21 @@ def test_html_file_suffix(app, status, warning):
             "search",
         ]
     }
+    lastmod = [
+        e.text
+        for e in doc.findall(".//{http://www.sitemaps.org/schemas/sitemap/0.9}lastmod")
+    ]
+    assert not lastmod
 
 
 @pytest.mark.sphinx(
     "dirhtml",
     freshenv=True,
-    confoverrides={"html_baseurl": "https://example.org/docs/", "language": "en"},
+    confoverrides={
+        "html_baseurl": "https://example.org/docs/",
+        "language": "en",
+        "sitemap_lastmod": "XX",
+    },
 )
 def test_simple_dirhtml(app, status, warning):
     app.warningiserror = True
@@ -99,6 +108,11 @@ def test_simple_dirhtml(app, status, warning):
             "search/",
         ]
     }
+    lastmod = [
+        e.text
+        for e in doc.findall(".//{http://www.sitemaps.org/schemas/sitemap/0.9}lastmod")
+    ]
+    assert len(lastmod) == len(urls)
 
 
 @pytest.mark.sphinx(
@@ -108,6 +122,7 @@ def test_simple_dirhtml(app, status, warning):
         "html_baseurl": "https://example.org/docs/",
         "language": "en",
         "sitemap_excludes": ["search.html", "genindex.html"],
+        "sitemap_lastmod": "2024-08-13",
     },
 )
 def test_simple_excludes(app, status, warning):
@@ -132,3 +147,14 @@ def test_simple_excludes(app, status, warning):
             "elitr",
         ]
     }
+
+    lastmod = [
+        e.text
+        for e in doc.findall(".//{http://www.sitemaps.org/schemas/sitemap/0.9}lastmod")
+    ]
+
+    assert len(lastmod) == len(urls)
+
+    assert set(lastmod) == {
+        app.builder.config.sitemap_lastmod,
+    }
diff --git a/tox.ini b/tox.ini
index ff201c2..e716c34 100644
--- a/tox.ini
+++ b/tox.ini
@@ -13,7 +13,7 @@ deps =
     sphinx7: Sphinx[test]~=7.0
     sphinxlast: Sphinx[test]
 commands =
-    pytest -W ignore::DeprecationWarning
+    pytest -W ignore::DeprecationWarning {posargs}
 
 [flake8]
 max-line-length = 100