Of potential hydrogen storage materials, pure magnesium would be best from the standpoint of hydrogen capacity per unit mass. However, pure magnesium has poor hydriding kinetics. Alloying magnesium with nickel and other transition metals aids catalysis of the hydrogen dissociative chemisorption and yields other benefits by lowering the dehydrogenation temperature, although at the expense of decreased storage capacity. Magnesium-nickel alloys with about one percent nickel prepared by ball-milling yield the most significant improvements in hydrogen storage behavior relative to pure magnesium.