diff --git a/README.md b/README.md
index 12289672..7e0b80e2 100644
--- a/README.md
+++ b/README.md
@@ -675,6 +675,17 @@ header('Location: ' . $ssoBuiltUrl);
 exit();
 ```
 
+If a check on the future SAMLResponse IssueInstant and the AuthNRequest IssueInstant to be sent is required, that AuthNRequest IssueInstant must to be extracted and saved.
+
+```php
+$ssoBuiltUrl = $auth->login(null, array(), false, false, true);
+$_SESSION['AuthNRequestIssueInstant'] = $auth->getLastRequestIssueInstant();
+header('Pragma: no-cache');
+header('Cache-Control: no-cache, must-revalidate');
+header('Location: ' . $ssoBuiltUrl);
+exit();
+````
+
 #### The SP Endpoints ####
 
 Related to the SP there are three important views: The metadata view, the ACS view and the SLS view. The toolkit
@@ -743,8 +754,15 @@ if (isset($_SESSION) && isset($_SESSION['AuthNRequestID'])) {
     $requestID = null;
 }
 
-$auth->processResponse($requestID);
+if (isset($_SESSION) && isset($_SESSION['AuthNRequestIssueInstant'])) {
+    $requestIssueInstant = $_SESSION['AuthNRequestIssueInstant'];
+} else {
+    $requestIssueInstant = null;
+}
+
+$auth->processResponse($requestID, $requestIssueInstant);
 unset($_SESSION['AuthNRequestID']);
+unset($_SESSION['AuthNRequestIssueInstant']);
 
 $errors = $auth->getErrors();
 
@@ -884,8 +902,13 @@ if (isset($_SESSION) && isset($_SESSION['LogoutRequestID'])) {
 } else {
     $requestID = null;
 }
+if (isset($_SESSION) && isset($_SESSION['LogoutRequestIssueInstant'])) {
+    $requestIssueInstant = $_SESSION['LogoutRequestIssueInstant'];
+} else {
+    $requestIssueInstant = null;
+}
 
-$auth->processSLO(false, $requestID);
+$auth->processSLO(false, $requestID, false, null, false, $requestIssueInstant);
 
 $errors = $auth->getErrors();
 
@@ -1058,6 +1081,17 @@ header('Location: ' . $sloBuiltUrl);
 exit();
 ```
 
+If a check on the future LogoutResponse IssueInstant and the LogoutRequest IssueInstant to be sent is required, that LogoutRequest IssueInstant must to be extracted and saved.
+
+```php
+$sloBuiltUrl = $auth->logout(null, $paramters, $nameId, $sessionIndex, true);
+$_SESSION['LogoutRequestIssueInstant'] = $auth->getLastRequestIssueInstant();
+header('Pragma: no-cache');
+header('Cache-Control: no-cache, must-revalidate');
+header('Location: ' . $sloBuiltUrl);
+exit();
+````
+
 #### Example of a view that initiates the SSO request and handles the response (is the acs target) ####
 
 We can code a unique file that initiates the SSO process, handle the response, get the attributes, initiate
@@ -1310,12 +1344,12 @@ Main class of OneLogin PHP Toolkit
  * `getErrors` - Returns if there were any error
  * `getSSOurl` - Gets the SSO url.
  * `getSLOurl` - Gets the SLO url.
- * `getLastRequestID` - The ID of the last Request SAML message generated.
  * `buildRequestSignature` - Generates the Signature for a SAML Request
  * `buildResponseSignature` - Generates the Signature for a SAML Response
  * `getSettings` - Returns the settings info
  * `setStrict` - Set the strict mode active/disable
  * `getLastRequestID` - Gets the ID of the last AuthNRequest or LogoutRequest generated by the Service Provider.
+ * `getLastRequestIssueInstant` - Gets the IssueInstant attribute of the last AuthNRequest or LogoutRequest generated by the Service Provider.
  * `getLastRequestXML` - Returns the most recently-constructed/processed XML SAML request (AuthNRequest, LogoutRequest)
  * `getLastResponseXML` - Returns the most recently-constructed/processed XML SAML response (SAMLResponse, LogoutResponse). If the SAMLResponse had an encrypted assertion, decrypts it.
 
diff --git a/demo1/index.php b/demo1/index.php
index 2400451f..ac93f58b 100644
--- a/demo1/index.php
+++ b/demo1/index.php
@@ -22,6 +22,14 @@
     # header('Location: ' . $ssoBuiltUrl);
     # exit();
 
+    # If AuthNRequest IssueInstant need to be saved in order to later validate it, do instead
+    # $ssoBuiltUrl = $auth->login(null, array(), false, false, true);
+    # $_SESSION['AuthNRequestIssueInstant'] = $auth->getLastRequestIssueInstant();
+    # header('Pragma: no-cache');
+    # header('Cache-Control: no-cache, must-revalidate');
+    # header('Location: ' . $ssoBuiltUrl);
+    # exit();
+
 } else if (isset($_GET['sso2'])) {
     $returnTo = $spBaseUrl.'/demo1/attrs.php';
     $auth->login($returnTo);
@@ -58,6 +66,14 @@
     # header('Location: ' . $sloBuiltUrl);
     # exit();
 
+    # If LogoutRequest IssueInstant need to be saved in order to later validate it, do instead
+    # $sloBuiltUrl = $auth->logout(null, $paramters, $nameId, $sessionIndex, true);
+    # $_SESSION['LogoutRequestIssueInstant'] = $auth->getLastRequestIssueInstant();
+    # header('Pragma: no-cache');
+    # header('Cache-Control: no-cache, must-revalidate');
+    # header('Location: ' . $sloBuiltUrl);
+    # exit();
+
 } else if (isset($_GET['acs'])) {
     if (isset($_SESSION) && isset($_SESSION['AuthNRequestID'])) {
         $requestID = $_SESSION['AuthNRequestID'];
@@ -65,7 +81,13 @@
         $requestID = null;
     }
 
-    $auth->processResponse($requestID);
+    if (isset($_SESSION) && isset($_SESSION['AuthNRequestIssueInstant'])) {
+        $requestIssueInstant = $_SESSION['AuthNRequestIssueInstant'];
+    } else {
+        $requestIssueInstant = null;
+    }
+
+    $auth->processResponse($requestID, $requestIssueInstant);
 
     $errors = $auth->getErrors();
 
@@ -95,7 +117,13 @@
         $requestID = null;
     }
 
-    $auth->processSLO(false, $requestID);
+    if (isset($_SESSION) && isset($_SESSION['LogoutRequestIssueInstant'])) {
+        $requestIssueInstant = $_SESSION['LogoutRequestIssueInstant'];
+    } else {
+        $requestIssueInstant = null;
+    }
+
+    $auth->processSLO(false, $requestID, false, null, false, $requestIssueInstant);
     $errors = $auth->getErrors();
     if (empty($errors)) {
         echo '<p>Sucessfully logged out</p>';
diff --git a/lib/Saml2/Auth.php b/lib/Saml2/Auth.php
index 591ffd37..4c2f2de6 100644
--- a/lib/Saml2/Auth.php
+++ b/lib/Saml2/Auth.php
@@ -123,6 +123,13 @@ class OneLogin_Saml2_Auth
      */
     private $_lastRequestID;
 
+    /**
+     * Last AuthNRequest or LogoutRequest IssueInstant generated by this Service Provider
+     *
+     * @var string
+     */
+    private $_lastRequestIssueInstant;
+
     /**
      * The most recently-constructed/processed XML SAML request
      * (AuthNRequest, LogoutRequest)
@@ -189,7 +196,7 @@ public function setStrict($value)
      * @throws OneLogin_Saml2_Error
      * @throws OneLogin_Saml2_ValidationError
      */
-    public function processResponse($requestId = null)
+    public function processResponse($requestId = null, $requestIssueInstant = null)
     {
         $this->_errors = array();
         $this->_errorReason = null;
@@ -198,7 +205,7 @@ public function processResponse($requestId = null)
             $response = new OneLogin_Saml2_Response($this->_settings, $_POST['SAMLResponse']);
             $this->_lastResponse = $response->getXMLDocument();
 
-            if ($response->isValid($requestId)) {
+            if ($response->isValid($requestId, $requestIssueInstant)) {
                 $this->_attributes = $response->getAttributes();
                 $this->_attributesWithFriendlyName = $response->getAttributesWithFriendlyName();
                 $this->_nameid = $response->getNameId();
@@ -237,14 +244,14 @@ public function processResponse($requestId = null)
      *
      * @throws OneLogin_Saml2_Error
      */
-    public function processSLO($keepLocalSession = false, $requestId = null, $retrieveParametersFromServer = false, $cbDeleteSession = null, $stay = false)
+    public function processSLO($keepLocalSession = false, $requestId = null, $retrieveParametersFromServer = false, $cbDeleteSession = null, $stay = false, $requestIssueInstant = null)
     {
         $this->_errors = array();
         $this->_errorReason = null;
         if (isset($_GET['SAMLResponse'])) {
             $logoutResponse = new OneLogin_Saml2_LogoutResponse($this->_settings, $_GET['SAMLResponse']);
             $this->_lastResponse = $logoutResponse->getXML();
-            if (!$logoutResponse->isValid($requestId, $retrieveParametersFromServer)) {
+            if (!$logoutResponse->isValid($requestId, $retrieveParametersFromServer, $requestIssueInstant)) {
                 $this->_errors[] = 'invalid_logout_response';
                 $this->_errorReason = $logoutResponse->getError();
             } else if ($logoutResponse->getStatus() !== OneLogin_Saml2_Constants::STATUS_SUCCESS) {
@@ -497,6 +504,7 @@ public function login($returnTo = null, $parameters = array(), $forceAuthn = fal
 
         $this->_lastRequest = $authnRequest->getXML();
         $this->_lastRequestID = $authnRequest->getId();
+        $this->_lastRequestIssueInstant = $authnRequest->getIssueInstant();
 
         $samlRequest = $authnRequest->getRequest();
         $parameters['SAMLRequest'] = $samlRequest;
@@ -554,6 +562,7 @@ public function logout($returnTo = null, $parameters = array(), $nameId = null,
 
         $this->_lastRequest = $logoutRequest->getXML();
         $this->_lastRequestID = $logoutRequest->id;
+        $this->_lastRequestIssueInstant = $logoutRequest->getIssueInstant();
 
         $samlRequest = $logoutRequest->getRequest();
 
@@ -624,6 +633,16 @@ public function getLastRequestID()
         return $this->_lastRequestID;
     }
 
+    /**
+     * Gets the IssueInstant of the last AuthNRequest or LogoutRequest generated by the Service Provider.
+     *
+     * @return string The IssueInstant of the Request SAML message.
+     */
+    public function getLastRequestIssueInstant()
+    {
+        return $this->_lastRequestIssueInstant;
+    }
+
     /**
      * Generates the Signature for a SAML Request
      *
diff --git a/tests/src/OneLogin/Saml2/AuthTest.php b/tests/src/OneLogin/Saml2/AuthTest.php
index 94e3872f..d9f464ef 100644
--- a/tests/src/OneLogin/Saml2/AuthTest.php
+++ b/tests/src/OneLogin/Saml2/AuthTest.php
@@ -57,6 +57,22 @@ public function testGetLastRequestID()
         $this->assertNotEquals($id1, $id2);
     }
 
+    /**
+    * Tests the getLastRequestIssueInstant method of the OneLogin_Saml2_Auth class
+    *
+    * @covers OneLogin_Saml2_Auth::getLastRequestIssueInstant
+    */
+    public function testGetLastRequestIssueInstant()
+    {
+        $targetSSOURL = $this->_auth->login(null, array(), false, false, true, false, false);
+        $issueInstant1 = $this->_auth->getLastRequestIssueInstant();
+        $this->assertNotNull($issueInstant1);
+
+        $targetSLOURL = $this->_auth->logout(null, array(), null, null, true, null, null);
+        $issueInstant2 = $this->_auth->getLastRequestIssueInstant();
+        $this->assertNotNull($issueInstant2);
+    }
+
     /**
     * Tests the getSSOurl method of the OneLogin_Saml2_Auth class
     *