diff --git a/.changeset/hide-gpt-5-5-pro.md b/.changeset/hide-gpt-5-5-pro.md
new file mode 100644
index 00000000000..68aa099db8e
--- /dev/null
+++ b/.changeset/hide-gpt-5-5-pro.md
@@ -0,0 +1,6 @@
+---
+"@kilocode/cli": patch
+"kilo-code": patch
+---
+
+Hide gpt-5.5-pro from the model picker when using ChatGPT OAuth login, since Codex rejects it with HTTP 400.
diff --git a/packages/opencode/src/plugin/openai/codex.ts b/packages/opencode/src/plugin/openai/codex.ts
index 9eb9710b21a..9d9ef12116f 100644
--- a/packages/opencode/src/plugin/openai/codex.ts
+++ b/packages/opencode/src/plugin/openai/codex.ts
@@ -29,6 +29,11 @@ const ALLOWED_MODELS = new Set([
   "gpt-5.2-codex",
   // kilocode_change end
 ])
+// kilocode_change start
+const DISALLOWED_MODELS = new Set([
+  "gpt-5.5-pro",
+])
+// kilocode_change end
 
 interface PkceCodes {
   verifier: string
@@ -394,6 +399,7 @@ export async function CodexAuthPlugin(input: PluginInput, options: CodexAuthPlug
           Object.entries(provider.models)
             .filter(([, model]) => {
               if (ALLOWED_MODELS.has(model.api.id)) return true
+              if (DISALLOWED_MODELS.has(model.api.id)) return false // kilocode_change
               const match = model.api.id.match(/^gpt-(\d+\.\d+)/)
               return match ? parseFloat(match[1]) > 5.4 : false
             })
diff --git a/packages/opencode/test/plugin/codex.test.ts b/packages/opencode/test/plugin/codex.test.ts
index a375fe4ee10..0be3ab63bbd 100644
--- a/packages/opencode/test/plugin/codex.test.ts
+++ b/packages/opencode/test/plugin/codex.test.ts
@@ -122,6 +122,68 @@ describe("plugin.codex", () => {
     })
   })
 
+  // kilocode_change start
+  describe("models filter", () => {
+    test("filters out disallowed models for oauth users", async () => {
+      const hooks = await CodexAuthPlugin({} as never)
+      const provider = await hooks.provider!.models!({
+        id: "openai",
+        baseURL: "",
+        apiKey: "",
+        models: {
+          "gpt-5.5-pro": {
+            id: "gpt-5.5-pro",
+            api: { id: "gpt-5.5-pro" },
+          } as never,
+          "gpt-5.5": {
+            id: "gpt-5.5",
+            api: { id: "gpt-5.5" },
+          } as never,
+          "gpt-5.4-mini": {
+            id: "gpt-5.4-mini",
+            api: { id: "gpt-5.4-mini" },
+          } as never,
+          "gpt-5.1-codex": {
+            id: "gpt-5.1-codex",
+            api: { id: "gpt-5.1-codex" },
+          } as never,
+          "other-model": {
+            id: "other-model",
+            api: { id: "other-model" },
+          } as never,
+        },
+      } as never, { auth: { type: "oauth" } } as never)
+      expect(provider).not.toHaveProperty(["gpt-5.5-pro"])
+      expect(provider).toHaveProperty(["gpt-5.5"])
+      expect(provider).toHaveProperty(["gpt-5.4-mini"])
+      expect(provider).toHaveProperty(["gpt-5.1-codex"])
+      expect(provider).not.toHaveProperty(["other-model"])
+    })
+
+    test("passes through all models when not using oauth", async () => {
+      const hooks = await CodexAuthPlugin({} as never)
+      const models = {
+        "gpt-5.5-pro": {
+          id: "gpt-5.5-pro",
+          api: { id: "gpt-5.5-pro" },
+        } as never,
+        "other-model": {
+          id: "other-model",
+          api: { id: "other-model" },
+        } as never,
+      }
+      const provider = await hooks.provider!.models!({
+        id: "openai",
+        baseURL: "",
+        apiKey: "",
+        models,
+      } as never, { auth: { type: "api", key: "sk-test" } } as never)
+      expect(provider).toHaveProperty(["gpt-5.5-pro"])
+      expect(provider).toHaveProperty(["other-model"])
+    })
+  })
+  // kilocode_change end
+
   test("installs websocket transport only when experimental websockets are enabled", async () => {
     const disabled = await CodexAuthPlugin({} as never)
     const enabled = await CodexAuthPlugin({} as never, { experimentalWebSockets: true })