A series of bimetallic 10%Ni-xIr/C (x = 0.5, 1.0, 1.5, 2.0 wt%) and monometallic 10%Ni/C and 2%Ir/C catalysts were prepared through the impregnation-reduction method modified by adding the ionic surfactant hexadecyltrimethylammonium bromide (CTAB) as the stabilizing agent during the impregnation. Their catalytic performance was tested by HI decomposition under atmospheric pressure at 400 degrees C and 500 degrees C. X-ray diffraction, Brunauer-Emmett-Teller surface area, transmission electron microscopy, and X-ray photoelectron spectroscopy were adopted to characterize the structure, specific surface area, morphology, and surface chemical state, respectively. Results showed that the addition of Ir metal and the use of CTAB played important roles in enhancing the activity and stability of the Ni-based bimetallic catalysts. Among all the catalysts tested, the bimetallic 10%Ni1.5%Ir/C catalyst presented excellent activity and stability for HI decomposition. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.