diff --git a/homeassistant/components/demo/light.py b/homeassistant/components/demo/light.py
index c859fef3b76..8bb4e403c3d 100644
--- a/homeassistant/components/demo/light.py
+++ b/homeassistant/components/demo/light.py
@@ -7,7 +7,7 @@ from typing import Any
 
 from homeassistant.components.light import (
     ATTR_BRIGHTNESS,
-    ATTR_COLOR_TEMP,
+    ATTR_COLOR_TEMP_KELVIN,
     ATTR_EFFECT,
     ATTR_HS_COLOR,
     ATTR_RGBW_COLOR,
@@ -28,7 +28,7 @@ LIGHT_COLORS = [(56, 86), (345, 75)]
 
 LIGHT_EFFECT_LIST = ["rainbow", "none"]
 
-LIGHT_TEMPS = [240, 380]
+LIGHT_TEMPS = [4166, 2631]
 
 SUPPORT_DEMO = {ColorMode.HS, ColorMode.COLOR_TEMP}
 SUPPORT_DEMO_HS_WHITE = {ColorMode.HS, ColorMode.WHITE}
@@ -185,8 +185,8 @@ class DemoLight(LightEntity):
         return self._rgbww_color
 
     @property
-    def color_temp(self) -> int:
-        """Return the CT color temperature."""
+    def color_temp_kelvin(self) -> int | None:
+        """Return the color temperature value in Kelvin."""
         return self._ct
 
     @property
@@ -216,9 +216,9 @@ class DemoLight(LightEntity):
         if ATTR_BRIGHTNESS in kwargs:
             self._brightness = kwargs[ATTR_BRIGHTNESS]
 
-        if ATTR_COLOR_TEMP in kwargs:
+        if ATTR_COLOR_TEMP_KELVIN in kwargs:
             self._color_mode = ColorMode.COLOR_TEMP
-            self._ct = kwargs[ATTR_COLOR_TEMP]
+            self._ct = kwargs[ATTR_COLOR_TEMP_KELVIN]
 
         if ATTR_EFFECT in kwargs:
             self._effect = kwargs[ATTR_EFFECT]
diff --git a/tests/components/google_assistant/test_smart_home.py b/tests/components/google_assistant/test_smart_home.py
index f1b7108c348..c5e17155067 100644
--- a/tests/components/google_assistant/test_smart_home.py
+++ b/tests/components/google_assistant/test_smart_home.py
@@ -402,7 +402,7 @@ async def test_query_message(hass: HomeAssistant) -> None:
     light.async_write_ha_state()
 
     light2 = DemoLight(
-        None, "Another Light", state=True, hs_color=(180, 75), ct=400, brightness=78
+        None, "Another Light", state=True, hs_color=(180, 75), ct=2500, brightness=78
     )
     light2.hass = hass
     light2.entity_id = "light.another_light"
@@ -410,7 +410,7 @@ async def test_query_message(hass: HomeAssistant) -> None:
     light2._attr_name = "Another Light"
     light2.async_write_ha_state()
 
-    light3 = DemoLight(None, "Color temp Light", state=True, ct=400, brightness=200)
+    light3 = DemoLight(None, "Color temp Light", state=True, ct=2500, brightness=200)
     light3.hass = hass
     light3.entity_id = "light.color_temp_light"
     light3._attr_device_info = None