Various ultra-fine oxide powders were prepared by ball milling process or calcinations process of metallic salts. Tantalum oxide and niobium oxide with nano-sized particles can be easily produced by those processes. Mg-Ni alloys with fine crystalline sizes were casted by melting and rapid solidification. The powders of Mg-Ni alloy with tantalum oxide or niobium oxides were prepared by mechanical grinding of Mg-Ni alloy and oxides. Hydriding rates of Mg-Ni alloy powders with tantalum oxide or niobium oxide were higher than those of Mg-Ni alloy powders due to catalytic effect. But, oxide additions to Mg-Ni alloy powders have minor effect on dehydriding rate of Mg-Ni alloy powders.