The effect of hydrogen isotopes on the thermodynamic parameters of desorption reaction in the Pd0.9X0.1-H-2/D-2 systems (X = Cu, Ag and Au) were investigated using Sieverts' apparatus. The hydrogen/deuterium desorption pressure-composition-temperature profiles generated in this study revealed substantial hydrogen isotope effect on the equilibrium plateau pressures with P-eq (D-2) > Peg (H-2). A correlation was observed for the trend in equilibrium plateau pressures with the unit cell sizes of the Pd0.9X0.1. alloys. Hydrogen isotope separation factor was determined for all these alloys and Pd0.9Cu0.1 alloy was found to have highest separation factor. The results of equilibrium plateau pressure and the separation factor for Pd(0.9)Cua(1) alloys merits its candidature for its applicability in gas chromatographic separation of hydrogen isotopes. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.