An innovative method, isothermal evaporation casting process (IECP), is developed to produce Mg2Ni alloy for mass production in this work. In the past, high vapor pressure of Mg was considered as a disadvantage for producing pure Mg2Ni alloy. However, this characteristic was used to develop a refinement procedure to separate primary Mg2Ni alloy from Mg/Mg2Ni eutectic matrix. Characteristics of as-cast specimens measured by X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and electron probe X-ray microanalyzer (EPMA) reveal that mass production of single phase Mg2Ni alloy was successfully fabricated by IECP. For every 4.0kg of raw materials, 2.6kg Mg2Ni alloy bulk was extracted at a yield of about 65%. The hydrogen storage capacity of the well-activated Mg2Ni alloy reaches 3.58 wt% at 300 degrees C under 40 atm H-2 atmosphere which is close to the theoretical capacity of 3.6 wt%. (c) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.