The present study reports the effect of Ni addition on the structure and hydrogen storage properties of Mg17Al12 alloy. The Mg17Al12 is synthesized by conventional melting process, and then ball-milled with Ni powder to form Mg17Al12-X wt.% Ni (X = 0, 10, 20) alloys. XRD results showed that the formation of stable Al3Ni and Al3Ni2 phases in the Ni-containing alloys after hydrogenation results in the production of surplus Mg during the desorption process. The catalytic effect of surplus Mg on the Ni-containing alloy is responsible for an enhancement of the hydrogen capacity and absorption rate, compared with ball-milled Mg17Al12 below 300 degrees C. (C) 2010 Published by Elsevier B.V.