Hydrogen permeable membranes composed of palladium-transition metal binary alloy were prepared. The palladium membrane alloyed with the transition metals of Group 3A that was able to dissolve more than 8 at% in palladium, silver and gold, showed higher hydrogen permeability compared to that of a pure palladium membrane. In particular, the hydrogen permeability of a palladium-holmium membrane was found to be the highest in this study, and two times higher than that of palladium-silver membrane.