You can try to create an observer in a module, preferrable your own module in the local code pool: <!-- app/code/local/Mymodule/etc/config.xml --> ... <global> <events> ... <sales_model_service_quote_submit_after> <observers> <clear_session> <class>Mymodule_Model_Observer</class> <method>clearCheckoutSession</method> </clear_session> </observers> </sales_model_service_quote_submit_after> </events> </global> ... Don't know how this works? See here: http://www.magentocommerce.com/wiki/5_-_modules_and_development/0_-_module_development_in_magento/customizing_magento_using_event-observer_method Once you declare the observer, build it out: <?php // app/code/local/Mymodule/Model/Observer.php class Mymodule_Model_Observer extends Varien_Event_Observer { public function clearCheckoutSession() { Mage::getSingleton('core/session')->clear(); // Or whatever you want to clear } } You'll want to customize this to your needs, obviously. And put some verification checks in there as well. Something to note is that the event we observe in the config XML, `sales_model_service_quote_submit_after`, is dispatched out of `Mage_Sales_Model_Service_Quote::submitOrder` - it is triggered **after** the order has completed. But, there are other events in there which might fit your need (eg: `checkout_type_onepage_save_order`).