Decomposition of hydrogen iodide (HI) for hydrogen production was conducted with a fixed-bed reactor in the range of 523-823 K. Effects of Pt loading amount, decomposition temperature and amount of adsorbed iodine on the decomposition of HI were investigated in an effort to improve the degree of HI conversion. To examine the change in the characteristics of the catalysts, SEM, EDS and XRD analyses were carried out before and after the HI decomposition reaction. The particle size of the platinum calculated using Scherrer's equation in the catalysts became larger and the surface morphology of the catalysts agglomerated into a lump after the HI decomposition reaction. HI conversion of all catalysts increased as the Pt loading and decomposition temperature increased. 5 wt% of Pt loading catalyst was appropriate for a HI decomposition reaction. The production of adsorbed iodine decreased as the decomposition temperature and Pt loading increased. This adsorption led to decline the catalytic activity during the HI decomposition reaction. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.