A material mixture is disclosed for storage of hydrogen for a hydrogen-using device and release of hydrogen on demand of the hydrogen-using device, especially by heating of the mixture. Such a mixture suitably comprises a solid hydrogen-containing lithium compound (e.g. LiBH.sub.4) and a solid magnesium compound, MgX, the magnesium compound being reactive with the lithium compound to release hydrogen and yield solid by products containing lithium and X. X may include one or more of F, Cl, OH, O, S, Se, Si, CO.sub.3, SO.sub.4, Cu, Ge, Ni, (OH)Cl, and P.sub.2O.sub.7.