It has been reported that intermetallic compounds could be used to improve hydrogen storage properties of Mg-based alloys. In this study, an attempt was made to synthesize the MgNi4Y compound from pure Ni, Mg and Y elemental powders via the combination of mechanical milling and heat treatment methods. In this regard, powders were ball milled in different conditions and then heat treated at 400 and 600 degrees C for 4 h to investigate the effect of temperature on the formation of MgNi4Y intermetallic compound. The characteristics of mixtures were evaluated via (XRD) and (SEM) methods. It was found from the results of XRD analysis that ternary intermetallic compound was not formed completely via ball milling alone. Nanostructured intermetallic compound was formed after heat treatment of milled powder at 600 degrees C for 25 h. Furthermore, addition of 5 and 10 wt% of the produced intermetallic compound to MgH2 decreased hydrogen desorption temperature and increased released hydrogen content. Copyright 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.