Isotopic exchange experiments were performed between gaseous hydrogen flows with constant rate through packed-powder beds of 0-year and 3.5-year tritium aged palladium deuteride. X-ray diffraction (XRD) indicated that the crystal lattice of palladium swelled due to the decayed He-3 which existed in the interstitial void of 3.5-year tritium aged palladium. The effluent curves of isotopic exchange reaction were simulated by plate theory of chromatography separation, and the reasons which influenced isotopic exchange performance were analyzed by rate theory of chromatography separation. After 3.5-year tritium aged, the isotopic exchange effluent curve went smooth, and the isotopic exchange efficiency declined. The results of isotopic exchange experiments accorded well with the theory simulated results. After exchange temperature raised, isotopic exchange performance of 3.5-year aged palladium increased, moreover, isotopic exchange performance of 3.5-year aged palladium was sensitive to temperature change. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.