Magnesium and magnesium-based alloys are considered attractive candidates as rechargeable hydrogen storage materials because of their high hydrogen storage capacities (theoretically up to 7.6 wt %), reversibility, and low cost. In this work, the hydrogenation of nanocrystalline magnesium at room temperature in the presence of TiH2 was studied. The magnesium was derived by dehydrogenation of nanostructured MgH2-0.1TiH(2) prepared by using an ultra-high-energy and high-pressure planetary milling technique. Significant uptake of hydrogen by magnesium at room temperature was observed. The results demonstrate that the nanostructured MgH2-0.1TiH(2) system is superior to undoped nano- or micrometer-scaled MgH2 with respect to the hydrogenation properties of magnesium at room temperature. This finding is potentially useful for a range of energy applications including mobile or stationary hydrogen fuel cells, cooling medium in electricity generation, and differential pressure compressors.