In this manuscript, the performance tests on the metal hydride based hydrogen storage devices employing Mg + 30% MmNi(5) and MmNi(4.08)Co(0.2)Mn(0.62)Al(0.1) are presented. Hydrogen storage performances of Mg + 30% MmNi(5) were investigated in the absorption and desorption temperatures ranges of 120-150 degrees C and 300-350 degrees C, respectively. The respective ranges for MmNi(4.08)Co(0.2)Mn(0.62)Al(0.1) are 30-180 C and 40-60 degrees C. For both the hydrides, supply pressures were varied from 10 to 30 bar. The maximum observed hydrogen storage capacities of Mg + 30% MmNi(5) at 20 bar supply pressure and 150 degrees C absorption temperature and MmNi(4.08)Co(0.2)Mn(0.62)Al(0.1) at 30 bar supply pressure, and 30 degrees C absorption temperature are 2.5 wt% and 1.2 wt%, respectively. For both the hydrides, the hydrogen storage capacities and the hydrogen absorption rates were found to increase with supply pressure. For a given supply pressure of 20 bar, the hydrogen storage capacity of Mg + 30% MmNi(5) was found to increase from 1.94 wt% at 120 degrees C to 2.5 wt% at 150 degrees C absorption temperature. The effect of supply pressure on the hydrogen storage capacities of Mg + 30% MmNi(5) at 150 degrees C absorption temperature and MmNi(4.08)Co(0.2)Mn(0.62)Al(0.1) at 30 degrees C absorption temperature was limited to 20 bar and 30 bar, respectively. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.