This article describes in situ heating and observation of a LiNH 2 –2LiH mixture in an environmental scanning electron microscope (ESEM). The LiNH 2 –2LiH mixture showed extensive morphological changes with heating and attendant hydrogen desorption. Static images and real-time movies were obtained during the dehydrogenation process. H 2 evolution commences at ∼150°C (LiNH 2 +2LiH→Li 2 NH+H 2 +LiH), and continues until ∼410°C. Dramatic morphological changes are observed at 220 and 410°C (Li 2 NH+LiH→Li 3 N+H 2 ). The material converts to a microcrystalline phase at higher temperatures (>500°C). The observed H 2 desorption and morphological changes occur at temperatures in good agreement with those measured by complementary analytical methods. This is the first time the major structural and morphological changes attendant on H 2 loss from this system have been observed in situ and in real time.