In this paper, a series of bimetallic palladium iridium catalysts supported on active carbon (Pd-Ir/C) were prepared by the impregnation-reduction method. Effects of the composition on the performance and stability of bimetallic catalysts in the decomposition of HI were investigated. X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) surface area were employed to characterize their structure, morphology and surface area, respectively. The results of activity tests indicated that all the bimetallic Pd-Ir catalysts were more active than the monometallic 5% Pd/C and 5% Ir/C catalysts at both 400 degrees C and 500 degrees C. Among Pd, In and binary Pd-Ir catalysts, the 4% Pd-1% Ir/C was the most active for HI catalytic decomposition at 400 C. Due to the low cost, high activity and good stability, the carbon supported bimetallic Pd In catalysts are more potential candidates to replace Pt/C for HI decomposition in the IS thermochemical cycle. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.