diff --git a/src/main/services/erp/erp-auth.ts b/src/main/services/erp/erp-auth.ts
new file mode 100644
index 0000000..2ded586
--- /dev/null
+++ b/src/main/services/erp/erp-auth.ts
@@ -0,0 +1,93 @@
+import { chromium, type Browser, type BrowserContext, type Page } from 'playwright';
+import { ERP_LOCATORS } from './locators';
+import type { ErpConfig, ErpSession } from '../../types/erp.types';
+
+/**
+ * ERP Authentication Service
+ * Manages login session and browser lifecycle
+ */
+export class ErpAuthService {
+  private config: ErpConfig;
+  private session: ErpSession | null = null;
+
+  constructor(config: ErpConfig) {
+    this.config = config;
+  }
+
+  /**
+   * Login to ERP system and establish session
+   */
+  async login(): Promise<ErpSession> {
+    if (this.session?.isLoggedIn) {
+      return this.session;
+    }
+
+    // Launch browser
+    const browser = await chromium.launch({
+      headless: false, // Set to true for production
+      slowMo: 100, // Slow down for debugging
+    });
+
+    const context = await browser.newContext({
+      acceptDownloads: true,
+      viewport: { width: 1920, height: 1080 },
+    });
+
+    const page = await context.newPage();
+
+    // Navigate to login page
+    await page.goto(this.config.url);
+
+    // Wait for login form
+    await page.waitForSelector(ERP_LOCATORS.login.usernameInput);
+
+    // Fill credentials
+    await page.fill(ERP_LOCATORS.login.usernameInput, this.config.username);
+    await page.fill(ERP_LOCATORS.login.passwordInput, this.config.password);
+
+    // Submit login
+    await page.click(ERP_LOCATORS.login.submitButton);
+
+    // Wait for main page to load
+    await page.waitForURL(`${this.config.url}/**`);
+    await page.waitForSelector(ERP_LOCATORS.main.mainIframe, { timeout: 10000 });
+
+    // Create session
+    this.session = {
+      browser,
+      context,
+      page,
+      isLoggedIn: true,
+    };
+
+    return this.session;
+  }
+
+  /**
+   * Close browser and cleanup session
+   */
+  async close(): Promise<void> {
+    if (this.session) {
+      await this.session.context.close();
+      await this.session.browser.close();
+      this.session = null;
+    }
+  }
+
+  /**
+   * Get current session (must be logged in first)
+   */
+  getSession(): ErpSession {
+    if (!this.session?.isLoggedIn) {
+      throw new Error('Not logged in. Call login() first.');
+    }
+    return this.session;
+  }
+
+  /**
+   * Check if session is active
+   */
+  isActive(): boolean {
+    return this.session?.isLoggedIn ?? false;
+  }
+}
diff --git a/tests/integration/erp-auth.test.ts b/tests/integration/erp-auth.test.ts
new file mode 100644
index 0000000..ae454e6
--- /dev/null
+++ b/tests/integration/erp-auth.test.ts
@@ -0,0 +1,40 @@
+import { describe, it, expect, beforeAll, afterAll } from 'vitest';
+import { ErpAuthService } from '../../src/main/services/erp/erp-auth';
+import type { ErpConfig } from '../../src/main/types/erp.types';
+
+describe('ERP Authentication Service (Integration)', () => {
+  let authService: ErpAuthService;
+  const config: ErpConfig = {
+    url: process.env.ERP_URL || '',
+    username: process.env.ERP_USERNAME || '',
+    password: process.env.ERP_PASSWORD || '',
+  };
+
+  beforeAll(() => {
+    if (!config.url || !config.username || !config.password) {
+      throw new Error('Missing ERP credentials in environment variables');
+    }
+    authService = new ErpAuthService(config);
+  });
+
+  it('should login successfully', async () => {
+    const session = await authService.login();
+
+    expect(session).toBeDefined();
+    expect(session.browser).toBeDefined();
+    expect(session.context).toBeDefined();
+    expect(session.page).toBeDefined();
+    expect(session.isLoggedIn).toBe(true);
+  }, 30000);
+
+  it('should navigate to main page after login', async () => {
+    const session = await authService.login();
+
+    const url = session.page.url();
+    expect(url).toContain(config.url);
+  }, 30000);
+
+  afterAll(async () => {
+    await authService?.close();
+  });
+});
diff --git a/tests/setup.ts b/tests/setup.ts
index 39aeacb..72646bb 100644
--- a/tests/setup.ts
+++ b/tests/setup.ts
@@ -1,8 +1,9 @@
 import { beforeAll, afterAll } from 'vitest';
 import dotenv from 'dotenv';
+import path from 'path';
 
-// Load environment variables
-dotenv.config({ path: '.env' });
+// Load environment variables from project root
+dotenv.config({ path: path.resolve(process.cwd(), '.env') });
 
 beforeAll(async () => {
   // Global test setup
diff --git a/tests/unit/erp-auth.unit.test.ts b/tests/unit/erp-auth.unit.test.ts
new file mode 100644
index 0000000..cb99d9c
--- /dev/null
+++ b/tests/unit/erp-auth.unit.test.ts
@@ -0,0 +1,59 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import { ErpAuthService } from '../../src/main/services/erp/erp-auth';
+import type { ErpConfig } from '../../src/main/types/erp.types';
+
+describe('ERP Authentication Service (Unit)', () => {
+  describe('Session Management', () => {
+    it('should create service instance with config', () => {
+      const config: ErpConfig = {
+        url: 'https://test.example.com',
+        username: 'testuser',
+        password: 'testpass',
+      };
+
+      const service = new ErpAuthService(config);
+
+      expect(service).toBeDefined();
+      expect(service.isActive()).toBe(false);
+    });
+
+    it('should throw error when getting session before login', () => {
+      const config: ErpConfig = {
+        url: 'https://test.example.com',
+        username: 'testuser',
+        password: 'testpass',
+      };
+
+      const service = new ErpAuthService(config);
+
+      expect(() => service.getSession()).toThrow('Not logged in. Call login() first.');
+    });
+
+    it('should report inactive status before login', () => {
+      const config: ErpConfig = {
+        url: 'https://test.example.com',
+        username: 'testuser',
+        password: 'testpass',
+      };
+
+      const service = new ErpAuthService(config);
+
+      expect(service.isActive()).toBe(false);
+    });
+  });
+
+  describe('Close Method', () => {
+    it('should handle close when no session exists', async () => {
+      const config: ErpConfig = {
+        url: 'https://test.example.com',
+        username: 'testuser',
+        password: 'testpass',
+      };
+
+      const service = new ErpAuthService(config);
+
+      // Should not throw when closing without session
+      await expect(service.close()).resolves.toBeUndefined();
+    });
+  });
+});