The effect of Cr as a catalyst in different proportions was investigated to monitor the hydrogen storage properties of Mg2Ni including their thermodynamic aspects. The P-C-T isotherms for absorption/desorption were measured at 225 degrees C, 250 degrees C, 275 degrees C and 300 degrees C temperatures. A significant increment in the plateau pressures at different temperature was observed, which shows the positive impact of Cr content in the formation of less stable hydrides. The active sites produced by the ball milling may be the reason for the formation of less stable hydrides. Decrements in the storage capacity with the Cr content were attributed to the formation of MgNi2 phase which does not absorb hydrogen at the employed temperature-pressure conditions. XRD and SEM technique were used to identify the structural and morphological changes induced by the hydrogenation cycles. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.