The invention provides methods, compositions, and systems for a reversible hydrogen storage material. The hydrogen storage material contains a lithium-magnesium compound, having LiMgN in a dehydrogenated state and a hydrogenated lithium magnesium product in a hydrogenated state, where the hydrogenated and dehydrogenated states are reversible. The lithium-magnesium compound is formed by reacting MgH.sub.2 and LiNH.sub.2 in a substantially inert atmosphere in amounts sufficient to obtain a hydrogen adsorption of at least 3 wt %, and in many cases up to about 8.1 wt %.
STATEMENT OF GOVERNMENT RIGHTS
 This invention was made with government support under Grant No. DE-FC36-05GO15069 awarded by U.S. Department of Energy. The government has certain rights to this invention.