Decomposition of HI is the key reaction of hydrogen production in the iodine-sulfur thermochemical water splitting cycle, so studies about the catalysts for HI decomposition have drawn increasing attention. In this study, a series of monometallic Pt/C((Pt/C-400, Pt/C-500, Pt/C-600, Pt/C-700 and Pt/C-800), Ir/C(Ir/C-400, Ir/C-500, Ir/C-600, Ir/C-700 and Ir/C-800) and bimetallic Pt-Ir catalysts supported on active carbon (Pt-Ir/C-400, Pt-Ir/C-500, Pt-Ir/C-600, Pt-Ir/C-700 and Pt-Ir/C-800 were prepared by the impregnation-reduction-calcination method. Their catalytic activities were evaluated for HI decomposition in a fixed bed reactor at 400 and 500 degrees C under atmospheric pressure. Their structures, metal particles size and distribution, and specific surface area were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) surface area, respectively. The results showed that the bimetallic Pt-Ir catalyst had the excellent stability in terms of the anti-sintering structure and catalytic activity. Therefore, the bimetallic Pt-Ir catalysts are the good candidates to take the place of the traditional monometallic Pt/C catalyst for catalyzing the HI decomposition. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.