diff --git a/src/main/java/de/w665/sharepulse/service/AuthenticationService.java b/src/main/java/de/w665/sharepulse/service/AuthenticationService.java
index 5ef2378..08a47b6 100644
--- a/src/main/java/de/w665/sharepulse/service/AuthenticationService.java
+++ b/src/main/java/de/w665/sharepulse/service/AuthenticationService.java
@@ -40,7 +40,10 @@ public class AuthenticationService {
         this.secretKey = Keys.hmacShaKeyFor(encodedKey);
     }
 
-    public String authenticate(String username, String password) {
+    public String authenticate(String username, String password, long... expirationTime/*FOR TESTING VALIDITY*/) {
+        if(expirationTime.length > 0) {
+            this.expirationTime = expirationTime[0];
+        }
         Optional<User> user = userRepository.retrieveUserByUsername(username);
         if (user.isPresent() && passwordEncoder.matches(password, user.get().getPassword())) {
             return generateToken(username);
@@ -64,8 +67,8 @@ public class AuthenticationService {
     public boolean validateToken(String token) {
         try {
             Jwt<?,?> jwt = Jwts.parser().verifyWith(secretKey).build().parseSignedClaims(token);
-            // TODO: Check if token is expired
-            return true;
+            Claims claims = (Claims) jwt.getPayload();
+            return !claims.getExpiration().before(new Date()); // Checks if the token is expired too
         } catch (Exception e) {
             return false;
         }
diff --git a/src/test/java/de/w665/sharepulse/AuthenticationServiceTest.java b/src/test/java/de/w665/sharepulse/AuthenticationServiceTest.java
index 36d40c2..42ee008 100644
--- a/src/test/java/de/w665/sharepulse/AuthenticationServiceTest.java
+++ b/src/test/java/de/w665/sharepulse/AuthenticationServiceTest.java
@@ -11,6 +11,7 @@ import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.mock.mockito.MockBean;
 import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
 
+import java.util.Date;
 import java.util.Optional;
 
 import static org.junit.jupiter.api.Assertions.*;
@@ -26,6 +27,9 @@ public class AuthenticationServiceTest {
     @Autowired
     private AuthenticationService authenticationService;
 
+    @Value("${secureapi.jwt.expiration}")
+    private long expirationTime;
+
     private User mockUser;
     private String username = "testUser";
     private String password = "testPass";
@@ -55,4 +59,13 @@ public class AuthenticationServiceTest {
         String invalidToken = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJ0ZXN0VXNlciJ9.WrongSignature";
         assertFalse(authenticationService.validateToken(invalidToken), "Token validation should return false for an invalid token");
     }
+
+    @Test
+    public void whenTokenIsExplicitlyExpired_thenValidateTokenShouldReturnFalse() throws InterruptedException {
+        long testExpirationTime = 1; // 1 millisecond
+        String token = authenticationService.authenticate("testUser", "testPass", testExpirationTime);
+        assertNotNull(token, "Token should not be null");
+        Thread.sleep(2); // Wait for 2 milliseconds to ensure the token has expired (Bad practice but easy)
+        assertFalse(authenticationService.validateToken(token), "Expired token should not be valid");
+    }
 }