diff --git a/extensions/inference-openai-extension/jest.config.js b/extensions/inference-openai-extension/jest.config.js
new file mode 100644
index 000000000..3e32adceb
--- /dev/null
+++ b/extensions/inference-openai-extension/jest.config.js
@@ -0,0 +1,9 @@
+/** @type {import('ts-jest').JestConfigWithTsJest} */
+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+  transform: {
+    'node_modules/@janhq/core/.+\\.(j|t)s?$': 'ts-jest',
+  },
+  transformIgnorePatterns: ['node_modules/(?!@janhq/core/.*)'],
+}
diff --git a/extensions/inference-openai-extension/src/OpenAIExtension.test.ts b/extensions/inference-openai-extension/src/OpenAIExtension.test.ts
new file mode 100644
index 000000000..4d46bc007
--- /dev/null
+++ b/extensions/inference-openai-extension/src/OpenAIExtension.test.ts
@@ -0,0 +1,54 @@
+/**
+ * @jest-environment jsdom
+ */
+jest.mock('@janhq/core', () => ({
+  ...jest.requireActual('@janhq/core/node'),
+  RemoteOAIEngine: jest.fn().mockImplementation(() => ({
+    onLoad: jest.fn(),
+    registerSettings: jest.fn(),
+    registerModels: jest.fn(),
+    getSetting: jest.fn(),
+    onSettingUpdate: jest.fn(),
+  })),
+}))
+import JanInferenceOpenAIExtension, { Settings } from '.'
+
+describe('JanInferenceOpenAIExtension', () => {
+  let extension: JanInferenceOpenAIExtension
+
+  beforeEach(() => {
+    // @ts-ignore
+    extension = new JanInferenceOpenAIExtension()
+  })
+
+  it('should initialize with settings and models', async () => {
+    await extension.onLoad()
+    // Assuming there are some default SETTINGS and MODELS being registered
+    expect(extension.apiKey).toBe(undefined)
+    expect(extension.inferenceUrl).toBe('')
+  })
+
+  it('should transform the payload for preview models', () => {
+    const payload: any = {
+      max_tokens: 100,
+      model: 'o1-mini',
+      // Add other required properties...
+    }
+
+    const transformedPayload = extension.transformPayload(payload)
+    expect(transformedPayload.max_completion_tokens).toBe(payload.max_tokens)
+    expect(transformedPayload).not.toHaveProperty('max_tokens')
+    expect(transformedPayload).toHaveProperty('max_completion_tokens')
+  })
+
+  it('should not transform the payload for non-preview models', () => {
+    const payload: any = {
+      max_tokens: 100,
+      model: 'non-preview-model',
+      // Add other required properties...
+    }
+
+    const transformedPayload = extension.transformPayload(payload)
+    expect(transformedPayload).toEqual(payload)
+  })
+})
diff --git a/extensions/inference-openai-extension/src/index.ts b/extensions/inference-openai-extension/src/index.ts
index 60446ccce..44c243adf 100644
--- a/extensions/inference-openai-extension/src/index.ts
+++ b/extensions/inference-openai-extension/src/index.ts
@@ -6,16 +6,17 @@
  * @module inference-openai-extension/src/index
  */
 
-import { RemoteOAIEngine, SettingComponentProps } from '@janhq/core'
+import { ModelRuntimeParams, PayloadType, RemoteOAIEngine } from '@janhq/core'
 
 declare const SETTINGS: Array<any>
 declare const MODELS: Array<any>
 
-enum Settings {
+export enum Settings {
   apiKey = 'openai-api-key',
   chatCompletionsEndPoint = 'chat-completions-endpoint',
 }
-
+type OpenAIPayloadType = PayloadType &
+  ModelRuntimeParams & { max_completion_tokens: number }
 /**
  * A class that implements the InferenceExtension interface from the @janhq/core package.
  * The class provides methods for initializing and stopping a model, and for making inference requests.
@@ -24,6 +25,7 @@ enum Settings {
 export default class JanInferenceOpenAIExtension extends RemoteOAIEngine {
   inferenceUrl: string = ''
   provider: string = 'openai'
+  previewModels = ['o1-mini', 'o1-preview']
 
   override async onLoad(): Promise<void> {
     super.onLoad()
@@ -63,4 +65,24 @@ export default class JanInferenceOpenAIExtension extends RemoteOAIEngine {
       }
     }
   }
+
+  /**
+   * Tranform the payload before sending it to the inference endpoint.
+   * The new preview models such as o1-mini and o1-preview replaced max_tokens by max_completion_tokens parameter.
+   * Others do not.
+   * @param payload 
+   * @returns 
+   */
+  transformPayload = (payload: OpenAIPayloadType): OpenAIPayloadType => {
+    // Transform the payload for preview models
+    if (this.previewModels.includes(payload.model)) {
+      const { max_tokens, ...params } = payload
+      return {
+        ...params,
+        max_completion_tokens: max_tokens,
+      }
+    }
+    // Pass through for non-preview models
+    return payload
+  }
 }
diff --git a/extensions/inference-openai-extension/tsconfig.json b/extensions/inference-openai-extension/tsconfig.json
index 2477d58ce..6db951c9e 100644
--- a/extensions/inference-openai-extension/tsconfig.json
+++ b/extensions/inference-openai-extension/tsconfig.json
@@ -10,5 +10,6 @@
     "skipLibCheck": true,
     "rootDir": "./src"
   },
-  "include": ["./src"]
+  "include": ["./src"],
+  "exclude": ["**/*.test.ts"]
 }