The method of hydriding combustion synthesis has been employed to prepare a ternary La 1 . 5 Mg 1 7 Ni 0 . 5 alloy that exhibits a large hydrogen storage capacity rapidly hydriding/dehydriding (H/D) kinetics at moderate conditions. The ternary La 1 . 5 Mg 1 7 Ni 0 . 5 alloy shows much better H/D kinetics than pure Mg, the binary Mg-Ni and Mg-La hydrogen storage alloys. It can absorb 5.40mass% H at 573K at excellent speed without any activation process. This composite absorbed 90% of its full hydrogen capacity (4.34mass% H) and desorbed the same percentage (4.12mass% H) in <5min at 523K, which is over 30 times faster than La 2 Mg 1 7 under the same conditions. Moreover, it can absorb 4.10mass% H and desorb 4.01mass% H at low temperature (473K), respectively. This attractive characteristic of the alloy can be explained by the catalytic action of LaNi 5 +LaH 3 +La as well as the multiphase structure which existed in the reaction process.