Hydrogen absorption mechanism in obliquely deposited MmNi(4.5)Al(0.5) thin films has been investigated in the present work. Thin films of 1150 angstrom thickness were prepared using the oblique deposition technique at different angles (theta = 0 degrees, 30 degrees, 45 degrees, 60 degrees and 75 degrees) simultaneously at a pressure of 10(-5) Torr and at room temperature. The thickness of the film was measured and controlled using a Quartz Crystal Thickness Monitor. Hydrogen charging of samples was carried out at 1 atm hydrogen pressure and discharging at 10-5 Torr pressure. This charging and discharging lead to saturation of thin films at 1 atm hydrogen pressure in the fourth cycle. The resistance of MmNi(4.5)Al(0.5) thin films increases on charging with I atm hydrogen and decreases on discharging at 10-5 Torr hydrogen pressure, which finally becomes constant in the fourth cycle indicating the saturation stage. Such types of thin films will find applications in the field of hydrogen energy where the amount of hydrogen required is limited to couple of grams only. (C) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.