The electrochemical characteristics of Mg2Ni-Ni alloys prepared by mechanical alloying (MA) using a planetary ball mill were investigated. The discharge capacity depends on the molar ratio in Ni and Mg2Ni, and it has a maximum value of about 480 mAh/g at the equimolar ratio of Ni/Mg2Ni. This discharge capacity (480 mAb/g) is about 74% of the theoretical one. The discharge capacity is reduced to about half within five cycles. Thus, the cycle time would be improved by inhibiting the oxidation of Mg2Ni.