Controlling the morphology of pentaerythritol tetranitrate (PETN) is an important aspect in the nanodetonics research area. Detonation properties are highly dependent on surface area and morphology of PETN. For the first time we show that changes in morphology can be modified at the nanoscale by using a heated atomic force microscope (AFM) cantilever. At temperatures of65C, faceting of PETN islands is observed, whereas at higher temperatures (124C) the height of the islands decrease by an order of magnitude.