Electrochemical and structural characteristics of amorphous Mg0.9Ti0.1Ni, Mg0.9V0.1Ni and Mg0.9Ti0.06V0.04Ni alloys prepared by mechanical alloying (MA) were investigated. In charge-discharge cycle tests, the decay of discharge capacity with increasing cycle number was suppressed by partial substitution with either Ti or V, and the alloy partially substituted with both Ti and V, Mg0.9Ti0.06V0.04Ni, exhibited further improved cycle performance. Results of X-ray diffractometry (XRD) indicated that the oxidation of Mg on the alloy surface during the charge-discharge cycles could be fairly suppressed by the partial substitution with both Ti and V: Moreover, it was found From Auger electron spectroscopy (AES) that thickness of oxidized surface layer of the MgNi alloy particle was decreased by the introduction of both Ti and V. It was suggested that composite oxide layer in which both Ti and V species existed might be very effective in suppressing the oxidation of the alloy surface, leading to the synergistic effect on charge-discharge cycle performance.