The global energy issues can be solved by the abundantly available hydrogen on earth. Light metals are a compact and safe medium for storing hydrogen. This makes them attractive for vehicular use. Unfortunately, hydrogen uptake and release is slow in light metals at practical temperature and pressure conditions. Catalysts are known to accelerate both processes. This research presents three mechanisms for catalyst actions: as grain refining agents, as a hydrogen vacancy formation facilitator, and (in its conventional role) as a hydrogen molecule splitter. Moreover, plentiful hydrogen vacancies are reported from experimental observations in nano-structured light metal hydrides. For specific storage systems, guidelines to select the optimal catalyst are developed based on the exploitable mechanisms.