diff --git a/CHANGELOG.md b/CHANGELOG.md
index 365a92d4..e3330d93 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,6 @@
 # Changelog
 
-## [0.9.0](https://github.com/googleapis/python-genai/compare/v0.8.0...v0.9.0) (2025-02-04)
+## [1.0.0rc0](https://github.com/googleapis/python-genai/compare/v0.8.0...v1.0.0rc0) (2025-02-04)
 
 
 ### Features
diff --git a/google/genai/version.py b/google/genai/version.py
index 41d16b43..f15943e7 100644
--- a/google/genai/version.py
+++ b/google/genai/version.py
@@ -13,4 +13,4 @@
 # limitations under the License.
 #
 
-__version__ = '0.9.0' # x-release-please-version
+__version__ = '1.0.0rc0' # x-release-please-version
diff --git a/pyproject.toml b/pyproject.toml
index b22698af..22e817a5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -3,7 +3,7 @@ requires = ["setuptools", "wheel"]
 
 [project]
 name = "google-genai"
-version = "0.9.0"
+version = "1.0.0rc0"
 description = "GenAI Python SDK"
 readme = "README.md"
 license = {text = "Apache-2.0"}