Density-functional theory calculations had been used to investigate the adsorption and dissociation of H2S on Mo(1 0 0) surface. Adsorption mechanisms of H2S, HS, S and H on the Mo(1 0 0) surface were analyzed. H2S was found to be adsorbed at bridge, hollow and top sites with adsorption energies of -1.25, -1.03 and -0.92 eV, respectively. HS was strongly chemically absorbed at hollow, bridge and top sites with adsorption energies of -4.51, -4.08 and -3.45 eV, respectively, and sulfur and hydrogen preferred to be absorbed at hollow and bridge sites, respectively. In addition, potential energy profiles of H2S dissociation on Mo(1 0 0) had been constructed by a climbing image nudged elastic band method. Four possible dissociation pathways of the first H2S dehydrogenation were examined with reaction barriers of 0.28, 0.37, 0.075, and 0.21 eV, respectively, while the energy barrier to break the S-H bond of HS with or without hydrogen co-adsorption was almost the same low. This work showed that the decomposition of H2S on the molybdenum surface was kinetically and thermodynamically facile. Local densities of electronic states were further used to characterize the interaction between H2S and substrate. (C) 2013 Elsevier B.V. All rights reserved.