In this study, we synthesized a nanostructured Mg 2 Ni alloy by means of hydriding combustion synthesis and subsequent mechanical grinding. Results on the structural change with mechanical grinding and the hydriding/dehydriding properties are presented. It was found that the nanostructured Mg 2 Ni showed great improvement in hydriding rates at 313 and 373K, and the reaction of dehydriding began at around 370K, which is 190K lower than that of the HCS product. Several factors were considered accounting for the enhancement in hydriding and dehydriding properties.