diff --git a/classes/loginflow/authcode.php b/classes/loginflow/authcode.php
index c81cc7d..09bb857 100644
--- a/classes/loginflow/authcode.php
+++ b/classes/loginflow/authcode.php
@@ -36,6 +36,7 @@
 use moodle_exception;
 use moodle_url;
 use pix_icon;
+use stdClass;
 
 defined('MOODLE_INTERNAL') || die();
 
@@ -395,7 +396,11 @@ protected function handleauthresponse(array $authparams) {
             // Otherwise it's a user logging in normally with OIDC.
             $this->handlelogin($oidcuniqid, $authparams, $tokenparams, $idtoken);
             if ($USER->id && $DB->record_exists('auth_oidc_token', ['userid' => $USER->id])) {
-                $DB->set_field('auth_oidc_token', 'sid', $sid, ['userid' => $USER->id]);
+                $authoidsidrecord = new stdClass();
+                $authoidsidrecord->userid = $USER->id;
+                $authoidsidrecord->sid = $sid;
+                $authoidsidrecord->timecreated = time();
+                $DB->insert_record('auth_oidc_sid', $authoidsidrecord);
             }
             redirect(core_login_get_return_url());
         }
@@ -792,7 +797,7 @@ protected function handlelogin(string $oidcuniqid, array $authparams, array $tok
                 $tokenrec = $DB->get_record('auth_oidc_token', ['id' => $tokenrec->id]);
                 // This should be already done in auth_plugin_oidc::user_authenticated_hook, but just in case...
                 if (!empty($tokenrec) && empty($tokenrec->userid)) {
-                    $updatedtokenrec = new \stdClass;
+                    $updatedtokenrec = new stdClass;
                     $updatedtokenrec->id = $tokenrec->id;
                     $updatedtokenrec->userid = $user->id;
                     $DB->update_record('auth_oidc_token', $updatedtokenrec);
diff --git a/classes/observers.php b/classes/observers.php
index a92cec8..a51781f 100644
--- a/classes/observers.php
+++ b/classes/observers.php
@@ -25,6 +25,9 @@
 
 namespace auth_oidc;
 
+use core\event\user_deleted;
+use core\event\user_loggedout;
+
 defined('MOODLE_INTERNAL') || die();
 
 require_once($CFG->dirroot.'/lib/filelib.php');
@@ -36,10 +39,10 @@ class observers {
     /**
      * Handle user_deleted event - clean up calendar subscriptions.
      *
-     * @param \core\event\user_deleted $event The triggered event.
+     * @param user_deleted $event The triggered event.
      * @return bool Success/Failure.
      */
-    public static function handle_user_deleted(\core\event\user_deleted $event) {
+    public static function handle_user_deleted(user_deleted $event) {
         global $DB;
         $userid = $event->objectid;
         $DB->delete_records('auth_oidc_token', ['userid' => $userid]);
diff --git a/classes/task/cleanup_oidc_sid.php b/classes/task/cleanup_oidc_sid.php
new file mode 100644
index 0000000..b6ed866
--- /dev/null
+++ b/classes/task/cleanup_oidc_sid.php
@@ -0,0 +1,49 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * A scheduled task to clean up oidc sid records.
+ *
+ * @package auth_oidc
+ * @author Lai Wei <lai.wei@enovation.ie>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @copyright (C) 2021 onwards Microsoft, Inc. (http://microsoft.com/)
+ */
+
+namespace auth_oidc\task;
+
+use core\task\scheduled_task;
+
+/**
+ * A scheduled task that cleans up OIDC SID records.
+ */
+class cleanup_oidc_sid extends scheduled_task {
+    /**
+     * Get a descriptive name for the task.
+     */
+    public function get_name() {
+        return get_string('task_cleanup_oidc_sid', 'auth_oidc');
+    }
+
+    /**
+     * Clean up OIDC SID records.
+     */
+    public function execute() {
+        global $DB;
+
+        $DB->delete_records_select('auth_oidc_sid', 'timecreated < ?', [strtotime('-1 day')]);
+    }
+}
diff --git a/db/install.xml b/db/install.xml
index a5c581b..93029ea 100644
--- a/db/install.xml
+++ b/db/install.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<XMLDB PATH="auth/oidc/db" VERSION="20231221" COMMENT="XMLDB file for Moodle auth/oidc plugin"
+<XMLDB PATH="auth/oidc/db" VERSION="20241127" COMMENT="XMLDB file for Moodle auth/oidc plugin"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="../../../lib/xmldb/xmldb.xsd"
 >
@@ -50,7 +50,6 @@
         <FIELD NAME="expiry" TYPE="int" LENGTH="10" NOTNULL="true" SEQUENCE="false" COMMENT="token expiry"/>
         <FIELD NAME="refreshtoken" TYPE="text" NOTNULL="true" SEQUENCE="false" COMMENT="refresh token"/>
         <FIELD NAME="idtoken" TYPE="text" NOTNULL="true" SEQUENCE="false" COMMENT="id token"/>
-        <FIELD NAME="sid" TYPE="char" LENGTH="36" NOTNULL="false" SEQUENCE="false"/>
       </FIELDS>
       <KEYS>
         <KEY NAME="primary" TYPE="primary" FIELDS="id"/>
@@ -61,5 +60,16 @@
         <INDEX NAME="username" UNIQUE="false" FIELDS="username"/>
       </INDEXES>
     </TABLE>
+    <TABLE NAME="auth_oidc_sid" COMMENT="Stores sid from IdP, to be used to find connected Moodle users when SLO is triggered from IdP.">
+      <FIELDS>
+        <FIELD NAME="id" TYPE="int" LENGTH="10" NOTNULL="true" SEQUENCE="true"/>
+        <FIELD NAME="userid" TYPE="int" LENGTH="20" NOTNULL="true" SEQUENCE="false"/>
+        <FIELD NAME="sid" TYPE="char" LENGTH="36" NOTNULL="true" SEQUENCE="false"/>
+        <FIELD NAME="timecreated" TYPE="int" LENGTH="10" NOTNULL="true" SEQUENCE="false"/>
+      </FIELDS>
+      <KEYS>
+        <KEY NAME="primary" TYPE="primary" FIELDS="id"/>
+      </KEYS>
+    </TABLE>
   </TABLES>
 </XMLDB>
diff --git a/db/tasks.php b/db/tasks.php
index 8ab8904..a254fce 100644
--- a/db/tasks.php
+++ b/db/tasks.php
@@ -35,4 +35,13 @@
         'dayofweek' => '*',
         'month' => '*',
     ],
+    [
+        'classname' => 'auth_oidc\task\cleanup_oidc_sid',
+        'blocking' => 0,
+        'minute' => '51',
+        'hour' => '*',
+        'day' => '*',
+        'dayofweek' => '*',
+        'month' => '*',
+    ],
 ];
diff --git a/db/upgrade.php b/db/upgrade.php
index 3276e64..b1a7436 100644
--- a/db/upgrade.php
+++ b/db/upgrade.php
@@ -94,7 +94,7 @@ function xmldb_auth_oidc_upgrade($oldversion) {
 
                 // Populate token oidcusername.
                 if (empty($user->oidcusername)) {
-                    $updatedtoken = new \stdClass;
+                    $updatedtoken = new stdClass;
                     $updatedtoken->id = $user->tokenid;
                     $updatedtoken->oidcusername = $oidcusername;
                     $DB->update_record('auth_oidc_token', $updatedtoken);
@@ -105,12 +105,12 @@ function xmldb_auth_oidc_upgrade($oldversion) {
                     // Old username, update to upn/sub.
                     if ($oidcusername != $user->username) {
                         // Update username.
-                        $updateduser = new \stdClass;
+                        $updateduser = new stdClass;
                         $updateduser->id = $user->userid;
                         $updateduser->username = $oidcusername;
                         $DB->update_record('user', $updateduser);
 
-                        $updatedtoken = new \stdClass;
+                        $updatedtoken = new stdClass;
                         $updatedtoken->id = $user->tokenid;
                         $updatedtoken->username = $oidcusername;
                         $DB->update_record('auth_oidc_token', $updatedtoken);
@@ -144,7 +144,7 @@ function xmldb_auth_oidc_upgrade($oldversion) {
         foreach ($authtokensrs as $authtokenrec) {
             $newusername = trim(\core_text::strtolower($authtokenrec->username));
             if ($newusername !== $authtokenrec->username) {
-                $updatedrec = new \stdClass;
+                $updatedrec = new stdClass;
                 $updatedrec->id = $authtokenrec->id;
                 $updatedrec->username = $newusername;
                 $DB->update_record('auth_oidc_token', $updatedrec);
@@ -181,7 +181,7 @@ function xmldb_auth_oidc_upgrade($oldversion) {
                       JOIN {user} u ON u.username = tok.username';
             $records = $DB->get_recordset_sql($sql);
             foreach ($records as $record) {
-                $newrec = new \stdClass;
+                $newrec = new stdClass;
                 $newrec->id = $record->id;
                 $newrec->userid = $record->userid;
                 $DB->update_record('auth_oidc_token', $newrec);
@@ -504,5 +504,48 @@ function xmldb_auth_oidc_upgrade($oldversion) {
         upgrade_plugin_savepoint(true, 2024042201, 'auth', 'oidc');
     }
 
+    if ($oldversion < 2024100702) {
+        // Define table auth_oidc_sid to be created.
+        $table = new xmldb_table('auth_oidc_sid');
+
+        // Adding fields to table auth_oidc_sid.
+        $table->add_field('id', XMLDB_TYPE_INTEGER, '10', null, XMLDB_NOTNULL, XMLDB_SEQUENCE, null);
+        $table->add_field('userid', XMLDB_TYPE_INTEGER, '20', null, XMLDB_NOTNULL, null, null);
+        $table->add_field('sid', XMLDB_TYPE_CHAR, '36', null, XMLDB_NOTNULL, null, null);
+        $table->add_field('timecreated', XMLDB_TYPE_INTEGER, '10', null, XMLDB_NOTNULL, null, null);
+
+        // Adding keys to table auth_oidc_sid.
+        $table->add_key('primary', XMLDB_KEY_PRIMARY, ['id']);
+
+        // Conditionally launch create table for auth_oidc_sid.
+        if (!$dbman->table_exists($table)) {
+            $dbman->create_table($table);
+        }
+
+        // Migrate existing sid values from auth_oidc_tokens to auth_oidc_sid.
+        $tokenrecords = $DB->get_records('auth_oidc_token');
+        foreach ($tokenrecords as $tokenrecord) {
+            if (isset($tokenrecord->sid) && $tokenrecord->sid) {
+                $sidrecord = new stdClass();
+                $sidrecord->userid = $tokenrecord->userid;
+                $sidrecord->sid = $tokenrecord->sid;
+                $sidrecord->timecreated = time();
+                $DB->insert_record('auth_oidc_sid', $sidrecord);
+            }
+        }
+
+        // Define field sid to be dropped from auth_oidc_token.
+        $table = new xmldb_table('auth_oidc_token');
+        $field = new xmldb_field('sid');
+
+        // Conditionally launch drop field sid.
+        if ($dbman->field_exists($table, $field)) {
+            $dbman->drop_field($table, $field);
+        }
+
+        // Oidc savepoint reached.
+        upgrade_plugin_savepoint(true, 2024100702, 'auth', 'oidc');
+    }
+
     return true;
 }
diff --git a/lang/en/auth_oidc.php b/lang/en/auth_oidc.php
index 123bbf8..1539773 100644
--- a/lang/en/auth_oidc.php
+++ b/lang/en/auth_oidc.php
@@ -207,6 +207,7 @@
 $string['event_debug'] = 'Debug message';
 
 $string['task_cleanup_oidc_state_and_token'] = 'Clean up OIDC state and invalid token';
+$string['task_cleanup_oidc_sid'] = 'Clean up OIDC SID records';
 
 $string['errorauthdisconnectemptypassword'] = 'Password cannot be empty';
 $string['errorauthdisconnectemptyusername'] = 'Username cannot be empty';
diff --git a/logout.php b/logout.php
index be5dc71..a652f78 100644
--- a/logout.php
+++ b/logout.php
@@ -32,14 +32,15 @@
 $sid = optional_param('sid', '', PARAM_TEXT);
 
 if ($sid) {
-    if ($authoidctokenrecord = $DB->get_record('auth_oidc_token', ['sid' => $sid])) {
-        if ($authoidctokenrecord->userid == $USER->id) {
+    if ($authoidcsidrecord = $DB->get_record('auth_oidc_sid', ['sid' => $sid])) {
+        if ($authoidcsidrecord->userid == $USER->id) {
             $authsequence = get_enabled_auth_plugins(); // Auths, in sequence.
             foreach ($authsequence as $authname) {
                 $authplugin = get_auth_plugin($authname);
                 $authplugin->logoutpage_hook();
             }
 
+            $DB->delete_records('auth_oidc_sid', ['sid' => $sid]);
             require_logout();
         }
     }
diff --git a/version.php b/version.php
index ff2197a..93b3be4 100644
--- a/version.php
+++ b/version.php
@@ -25,7 +25,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$plugin->version = 2024100700;
+$plugin->version = 2024100703;
 $plugin->requires = 2024100700;
 $plugin->release = '4.5.0';
 $plugin->component = 'auth_oidc';