NOVELTY - Hydrogen storage material (R1) comprises a hydride of lithium and magnesium.    USE - For reversibly storing hydrogen; for obtaining hydrogen-comprising gas; for fuelling hydrogen-burning engine; and for manufacturing a hydrogen battery and a hydrogen storage tank (claimed).    ADVANTAGE - The hydrogen storage material provides high storage capacity for hydrogen while allowing retrieval of the hydrogen from the storage material relatively low temperatures.    DETAILED DESCRIPTION - Hydrogen storage material (R1) comprises a hydride of lithium and magnesium, the material has the formula LixMgyHn.    x=0.17-0.93;    y=0.07-0.83;    n= not greater than (x+2y).    Provided that when n is not (x+2y) then x is y, x is 2y or 2x is y. INDEPENDENT CLAIMS are included for the following:    (1) preparing the hydrogen storage material (R1) either involving method (M1): contacting metallic Li and/or its hydride with metallic Mg and/or its hydride such that a hydride of lithium and magnesium is formed; or method (M2): vaporizing Li and Mg from at least one source and depositing the vaporized Li and Mg on a suitable substrate in presence of a hydrogen source;    (2) reversibly (M3) absorbing hydrogen using the hydrogen storage material (R1) involving contacting the hydrogen storage material with a hydrogen-comprising gas;    (3) obtaining (M4) a hydrogen-comprising gas from the hydrogen storage material (R1) involving desorbing hydrogen from the hydrogen storage material to obtain hydrogen gas and an at least partially dehydrided hydrogen storage material;    (4) reversibly (M5) desorbing and/or absorbing hydrogen using the hydrogen storage material (R1) involving dehydriding the hydrogen storage material by desorbing hydrogen from the hydrogen storage material to obtain hydrogen gas and a partially dehydrided hydrogen storage material, where the desorption is monitored and terminated such that, upon termination, n is at least 0.1(x+2y), and hydriding the partially dehydrided hydrogen storage material by contacting the partially dehydrided hydrogen storage material with a hydrogen-comprising gas to reversibly store hydrogen and to obtain an at least partially rehydrided hydrogen storage material;    (5) fuelling a hydrogen-burning engine involving desorbing hydrogen from the hydrogen storage material (R1) and feeding the desorbed hydrogen to the inlet of the hydrogen-burning engine.