In this study, Pt/Ce1-xZrx catalysts with different Zr mole concentration (x = 0, 0.2, 0.5, 0.8, 1) have been tested to evaluate their effects on hydrogen iodide (HI) decomposition for hydrogen production in the sulfur-iodine (SI or IS) cycle at various temperatures. The Pt/Ce1-xZrx catalysts strongly enhanced the HI conversion to H-2 by comparison with blank test, especially the Pt/Ce0.8Zr0.2 catalyst. BET, XRD, TEM, EDS, TPR were performed for catalysts characterization. It was found that, through introducing ZrO2 into Pt/CeO2, a synergistic effect between Pt and CeO2-ZrO2 solid solution was different from Pt and CeO2 yield, such as improvement of the thermal stability and increase of Pt-O-Ce reducibility. Among the three samples containing Zr, the one with 20 mol% displayed the best activity for hydrogen production. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.