diff --git a/launch/launch/actions/execute_process.py b/launch/launch/actions/execute_process.py
index c74d062d8..ed1a29ff0 100644
--- a/launch/launch/actions/execute_process.py
+++ b/launch/launch/actions/execute_process.py
@@ -377,25 +377,28 @@ def parse(
                     )
                 kwargs['respawn_delay'] = respawn_delay
 
-        if 'sigkill_timeout' not in ignore:
-            sigkill_timeout = entity.get_attr('sigkill_timeout', data_type=float, optional=True)
-            if sigkill_timeout is not None:
-                if sigkill_timeout < 0.0:
-                    raise ValueError(
-                        'Attribute sigkill_timeout of Entity node expected to be '
-                        'a non-negative value but got `{}`'.format(sigkill_timeout)
+        for timeout_name in ('sigkill_timeout', 'sigterm_timeout'):
+            if timeout_name in ignore:
+                continue
+            timeout = entity.get_attr(
+                timeout_name, data_type=float, optional=True, can_be_str=True)
+            if timeout is None:
+                continue
+            if isinstance(timeout, str):
+                parsed_timeout = parser.parse_if_substitutions(timeout)
+                if isinstance(parsed_timeout, str):
+                    raise TypeError(
+                        'Attribute {} of Entity node expected to be a float or substitution '
+                        'but got `{}`'.format(timeout_name, parsed_timeout)
                     )
-                kwargs['sigkill_timeout'] = str(sigkill_timeout)
-
-        if 'sigterm_timeout' not in ignore:
-            sigterm_timeout = entity.get_attr('sigterm_timeout', data_type=float, optional=True)
-            if sigterm_timeout is not None:
-                if sigterm_timeout < 0.0:
+                kwargs[timeout_name] = parsed_timeout
+            else:
+                if timeout < 0.0:
                     raise ValueError(
-                        'Attribute sigterm_timeout of Entity node expected to be '
-                        'a non-negative value but got `{}`'.format(sigterm_timeout)
+                        'Attribute {} of Entity node expected to be a non-negative value '
+                        'but got `{}`'.format(timeout_name, timeout)
                     )
-                kwargs['sigterm_timeout'] = str(sigterm_timeout)
+                kwargs[timeout_name] = str(timeout)
 
         if 'shell' not in ignore:
             shell = entity.get_attr('shell', data_type=bool, optional=True)
diff --git a/launch_xml/test/launch_xml/test_executable.py b/launch_xml/test/launch_xml/test_executable.py
index 647512842..6ba2ed314 100644
--- a/launch_xml/test/launch_xml/test_executable.py
+++ b/launch_xml/test/launch_xml/test_executable.py
@@ -18,6 +18,7 @@
 from pathlib import Path
 import textwrap
 
+from launch import LaunchContext
 from launch import LaunchService
 from launch.actions import Shutdown
 
@@ -85,5 +86,30 @@ def test_executable_on_exit():
     assert isinstance(sub_entities[0], Shutdown)
 
 
+def test_executable_timeout_substitutions():
+    xml_file = \
+        """\
+        <launch>
+            <executable cmd="echo" sigkill_timeout="$(var timeout)" sigterm_timeout="$(var timeout)"/>
+        </launch>
+        """  # noqa, line too long
+    xml_file = textwrap.dedent(xml_file)
+    root_entity, parser = load_no_extensions(io.StringIO(xml_file))
+    ld = parser.parse_description(root_entity)
+    executable = ld.entities[0]
+    context = LaunchContext()
+    context.launch_configurations['timeout'] = '3.5'
+    assert executable.sigkill_timeout[0].perform(context) == '3.5'
+    assert executable.sigterm_timeout[0].perform(context) == '3.5'
+
+
+@pytest.mark.parametrize('timeout_name', ('sigkill_timeout', 'sigterm_timeout'))
+def test_executable_invalid_timeout(timeout_name):
+    xml_file = '<launch><executable cmd="echo" {}="invalid"/></launch>'.format(timeout_name)
+    root_entity, parser = load_no_extensions(io.StringIO(xml_file))
+    with pytest.raises(TypeError, match=timeout_name):
+        parser.parse_description(root_entity)
+
+
 if __name__ == '__main__':
     test_executable()
diff --git a/launch_yaml/test/launch_yaml/test_executable.py b/launch_yaml/test/launch_yaml/test_executable.py
index 84bac7183..7e2f8c265 100644
--- a/launch_yaml/test/launch_yaml/test_executable.py
+++ b/launch_yaml/test/launch_yaml/test_executable.py
@@ -17,11 +17,14 @@
 import io
 import textwrap
 
+from launch import LaunchContext
 from launch import LaunchService
 from launch.actions import Shutdown
 
 from parser_no_extensions import load_no_extensions
 
+import pytest
+
 
 def test_executable():
     """Parse executable yaml example."""
@@ -82,5 +85,39 @@ def test_executable_on_exit():
     assert isinstance(sub_entities[0], Shutdown)
 
 
+def test_executable_timeout_substitutions():
+    yaml_file = \
+        """\
+        launch:
+        -   executable:
+                cmd: echo
+                sigkill_timeout: $(var timeout)
+                sigterm_timeout: $(var timeout)
+        """
+    yaml_file = textwrap.dedent(yaml_file)
+    root_entity, parser = load_no_extensions(io.StringIO(yaml_file))
+    ld = parser.parse_description(root_entity)
+    executable = ld.entities[0]
+    context = LaunchContext()
+    context.launch_configurations['timeout'] = '3.5'
+    assert executable.sigkill_timeout[0].perform(context) == '3.5'
+    assert executable.sigterm_timeout[0].perform(context) == '3.5'
+
+
+@pytest.mark.parametrize('timeout_name', ('sigkill_timeout', 'sigterm_timeout'))
+def test_executable_invalid_timeout(timeout_name):
+    yaml_file = \
+        """\
+        launch:
+        -   executable:
+                cmd: echo
+                {}: invalid
+        """.format(timeout_name)
+    yaml_file = textwrap.dedent(yaml_file)
+    root_entity, parser = load_no_extensions(io.StringIO(yaml_file))
+    with pytest.raises(TypeError, match=timeout_name):
+        parser.parse_description(root_entity)
+
+
 if __name__ == '__main__':
     test_executable()