In this paper, the electrochemical properties of Co-free AB 5 type MlNi ( 4 . 4 5 - x ) Mn 0 . 4 0 Al 0 . 1 5 Sn x (x=0.0-0.5) hydride electrode alloys, such as the activation characteristics, the electrochemical capacity, the charge-discharge curves, the cycling stability and the high-rate dischargeability, were investigated in detail. The results show that with the increase of Sn content in the alloy, the electrochemical cycling stability improve dramatically, but the electrochemical capacity and the high-rate dischargeability decrease markedly. The electrochemical studies show that, among the alloys investigated, MlNi 4 . 1 5 Mn 0 . 4 0 Al 0 . 1 5 Sn 0 . 3 alloy has the best comprehensive electrochemical properties, which can be activated in two cycles with the highest maximum discharge capacity (C m a x =295.0 mAh/g), good high-rate dischargeability (R 3 0 0 =96.67%) and the capacity retention of 70.45% after 300 charge-discharge cycles under the test condition of 1C current density.