Jira JQL that returns date of status change

There is no simple solution available in JIRA at the moment. See the issue https://jira.atlassian.com/browse/JRA-12825 for the whole discussion. The argumentation of Atlassian is the following:

• There exists a product Service Desk that implements the SLA feature expressed here.
• There are reports and additional plugins available that give similar information to this. See the JIRA Suite Utilities which give you a UI for each issue to see the transition summary.
• JQL (JIRA Query Language) was intended to select all issues that match a query, not to select special information to these issues. You have to use the configuration of the table, if it is included there as a field of the issue (which it is not).

In addition to the suggestions from mliebelt there is another at https://answers.atlassian.com/questions/128370/how-to-capture-date-of-state-change-in-jira. It requires JIRA Misc Workflow Extenstions and uses the "Copy value from field to field" function to capture the transition date in a custom field.