Mg(2)Ni-x mol% Mg(3)MnNi(2) (x = 0, 15, 30, 60, 100), the novel composite alloys employed for hydrogen storage electrode, have been successfully synthesized by a method combining electric resistance melting with isothermal evaporation casting process (IECP). X-ray diffraction (XRD) analysis results show that the composite alloys are composed of Mg(2)Ni phases and the new Mg(3)MnNi(2) phases. It is found on the electrochemical studies that maximum discharge capacities of the composite alloys increase with the increasing content of the Mg(3)MnNi(2) phase. The discharge capacity of the electrode alloy is effectively improved from 17 mAh g(-1) of the Mg(2)Ni alloy to 166 mAh g(-1) of the Mg(3)MnNi(2) alloy. Among these alloys, the Mg(3)MnNi(2) phase possesses a positive effect on the retardation of cycling capacity degradation rate of the electrode materials. Cyclic voltammetry (CV) results confirm that the increasing content of the Mg(3)MnNi(2) phase effectively improves the reaction activity of the electrode alloys. Surface analyses indicate that the Mg(3)MnNi(2) phase can enhance the anti-corrosive performance of the particle surface of these composite alloys. (C) 2009 Elsevier B. V. All rights reserved.