Mg2Ni alloy prepared by induction was ball-milled with 3 wt% metallic cobalt powder. The effect of the ball-milling on the alloy structure and surface image was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mixed alloy powders before and after ball-milling were pressed on to a porous nickel foam as the active material of a metal hydride electrode. Electrochemical characteristics of the two kinds of electrodes were investigated at 25°. The discharge capacity, cycle life and high-rate discharge ability showed that the electrode properties were improved greatly by the ball-milling of Mg2Ni and Co powder because of the changed structure and surface of the alloy. © 1998 Elsevier Science Ltd. All rights reserved.