Mg(100-x)Tix-10 wt % Pd alloys, with x ranging from 20 to 80, were prepared by ballmilling. Except for x = 20, a complete mechanical alloying between Mg and Ti was observed. X-ray diffraction analyses combined with Rietveld refinement show that the as-milled alloys are made of a mixture of hexagonal close-packed (hcp) and body-centered cubic (bcc) phases in various proportions and compositions depending on the Mg/Ti ratio in the initial mixture. Their hydrogen storage characteristics were investigated electrochemically in a KOH electrolyte. The number of activation cycles and the maximum discharge capacity value are strongly dependent on the material composition. The highest hydrogen discharge capacity (475 mAh g(-1)) is obtained with the Mg50Ti50-10 wt % Pd electrode. Structural analyses of a cycled Mg50Ti50-10 wt % Pd electrode show that both hcp and bcc Mg-Ti phases are transformed into a face-centered cubic phase upon cycling. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3236478] All rights reserved.