diff --git a/sdk/typescript/src/exec.ts b/sdk/typescript/src/exec.ts
index 45ae5fc6..5c7b1846 100644
--- a/sdk/typescript/src/exec.ts
+++ b/sdk/typescript/src/exec.ts
@@ -3,7 +3,7 @@ import path from "node:path";
 import readline from "node:readline";
 import { fileURLToPath } from "node:url";
 
-import { SandboxMode } from "./threadOptions";
+import { SandboxMode, ModelReasoningEffort } from "./threadOptions";
 
 export type CodexExecArgs = {
   input: string;
@@ -22,6 +22,8 @@ export type CodexExecArgs = {
   skipGitRepoCheck?: boolean;
   // --output-schema
   outputSchemaFile?: string;
+  // --config model_reasoning_effort
+  modelReasoningEffort?: ModelReasoningEffort;
 };
 
 const INTERNAL_ORIGINATOR_ENV = "CODEX_INTERNAL_ORIGINATOR_OVERRIDE";
@@ -56,6 +58,10 @@ export class CodexExec {
       commandArgs.push("--output-schema", args.outputSchemaFile);
     }
 
+    if (args.modelReasoningEffort) {
+      commandArgs.push("--config", `model_reasoning_effort="${args.modelReasoningEffort}"`);
+    }
+
     if (args.images?.length) {
       for (const image of args.images) {
         commandArgs.push("--image", image);
diff --git a/sdk/typescript/src/index.ts b/sdk/typescript/src/index.ts
index 8e6a71df..cfd0dc43 100644
--- a/sdk/typescript/src/index.ts
+++ b/sdk/typescript/src/index.ts
@@ -30,5 +30,10 @@ export { Codex } from "./codex";
 
 export type { CodexOptions } from "./codexOptions";
 
-export type { ThreadOptions, ApprovalMode, SandboxMode } from "./threadOptions";
+export type {
+  ThreadOptions,
+  ApprovalMode,
+  SandboxMode,
+  ModelReasoningEffort,
+} from "./threadOptions";
 export type { TurnOptions } from "./turnOptions";
diff --git a/sdk/typescript/src/thread.ts b/sdk/typescript/src/thread.ts
index 2306df25..08488521 100644
--- a/sdk/typescript/src/thread.ts
+++ b/sdk/typescript/src/thread.ts
@@ -85,6 +85,7 @@ export class Thread {
       workingDirectory: options?.workingDirectory,
       skipGitRepoCheck: options?.skipGitRepoCheck,
       outputSchemaFile: schemaPath,
+      modelReasoningEffort: options?.modelReasoningEffort,
     });
     try {
       for await (const item of generator) {
diff --git a/sdk/typescript/src/threadOptions.ts b/sdk/typescript/src/threadOptions.ts
index 7f01488d..53895c9a 100644
--- a/sdk/typescript/src/threadOptions.ts
+++ b/sdk/typescript/src/threadOptions.ts
@@ -2,9 +2,12 @@ export type ApprovalMode = "never" | "on-request" | "on-failure" | "untrusted";
 
 export type SandboxMode = "read-only" | "workspace-write" | "danger-full-access";
 
+export type ModelReasoningEffort = "minimal" | "low" | "medium" | "high";
+
 export type ThreadOptions = {
   model?: string;
   sandboxMode?: SandboxMode;
   workingDirectory?: string;
   skipGitRepoCheck?: boolean;
+  modelReasoningEffort?: ModelReasoningEffort;
 };
diff --git a/sdk/typescript/tests/run.test.ts b/sdk/typescript/tests/run.test.ts
index f495b1e6..f6eefa0c 100644
--- a/sdk/typescript/tests/run.test.ts
+++ b/sdk/typescript/tests/run.test.ts
@@ -223,6 +223,37 @@ describe("Codex", () => {
     }
   });
 
+  it("passes modelReasoningEffort to exec", async () => {
+    const { url, close } = await startResponsesTestProxy({
+      statusCode: 200,
+      responseBodies: [
+        sse(
+          responseStarted("response_1"),
+          assistantMessage("Reasoning effort applied", "item_1"),
+          responseCompleted("response_1"),
+        ),
+      ],
+    });
+
+    const { args: spawnArgs, restore } = codexExecSpy();
+
+    try {
+      const client = new Codex({ codexPathOverride: codexExecPath, baseUrl: url, apiKey: "test" });
+
+      const thread = client.startThread({
+        modelReasoningEffort: "high",
+      });
+      await thread.run("apply reasoning effort");
+
+      const commandArgs = spawnArgs[0];
+      expect(commandArgs).toBeDefined();
+      expectPair(commandArgs, ["--config", 'model_reasoning_effort="high"']);
+    } finally {
+      restore();
+      await close();
+    }
+  });
+
   it("writes output schema to a temporary file and forwards it", async () => {
     const { url, close, requests } = await startResponsesTestProxy({
       statusCode: 200,