The interaction of ammonia with binary hydrides (prototypically, the interaction of LiH with ammonia gas) is thought to be the predominant interaction for hydrogen production within the Li2NH - LiNH2 reversible hydrogen storage system. This interaction forms the basis for the development of new, mixed metal amides with lower temperature and more facile dehydrogenation / hydrogenation kinetics. A comprehensive understanding of the interaction of ammonia with binary and ternary hydrides, and in particular the roles of the various cationic species, protonic and hydritic deuterium and nucleophilic nitrogen is vital to allow the development of new, more effective hydrogen storage materials.