The electrochemical performance of double phase Mg-Ni alloy was characterized at 25°C and 70°C, in order to evaluate briefly its utility as negative electrode materials in nickel-metal hydride batteries. The results show that the electrochemical capacity of double phase Mg-Ni alloy is rarely low at 25°C, but increased rapidly when the temperature is enhanced, and the double phase MgNi alloy has its maximum capacity at the first discharge cycle, but the capacity degrades rapidly with cycling number.