Abstract: The present invention relates generally to a DEF tank hydraulic jack adapter plate. The adapter can be fixedly or removably attached to the top surface of an existing hydraulic jack such that the jack can be used to remove or replace a DEF tank from a diesel vehicle. Accordingly, the adapter secures a tank to the plate body of the adapter via a plurality of frame arms which attach to the vertical plates of the plate body. The adapter ensures the tank is retained upon the adapter and subsequently on the jack.