Periodic　density　functional　theory　calculations　have　been　performed　to　investigate　the　adsorption　structures　and　dissociative　reaction　pathways　for　H2S　molecule　on　Ni(111),Pd(111)　and　Ni/Pd(111)　monolayer　bimetallic　surfaces　with　surface　monolayer　and　subsurface　monolayer　structures.　Our　results　indicate　that,　for　the　molecular　adsorption　mode,　the　introducing　Pd　atoms　on　Ni(111)　can　enhance　the　binding　strength　between　H2S　and　the　surface,　while　an　opposite　effect　is　achieved　when　the　Ni　monolayer　is　formed　on　Pd(111)　surface.　The　decompositions　of　H2S　molecule　on　all　Ni/Pd(111)　surfaces　are　exothermic,　especially　for　the　surfaces　that　the　top　layer　is　composed　of　Ni　atoms.　According　to　the　predicted　minimum　energy　paths　that　connect　the　molecular　and　dissociative　states,　two　elementary　steps　are　found　for　all　Ni/Pd(111)　metal　surfaces,　and　the　breaking　of　the　first　H-S　bond　is　the　rate-determining　step　for　the　H2S　dissociation.　Our　results　reveal　that　in　most　cases,　the　decomposition　of　H2S　molecule　on　the　monometallic　and　Ni/Pd(111)　monolayer　bimetallic　surfaces　is　easy　to　happen.　However,　on　the　monolayer　Ni-Pd(　111)　surface,　there　is　a　competition　between　the　trapping-desorption　channel　and　activated　dissociation　channel,　which　implies　that　depositing　one　monolayer　Ni　on　a　Pd(111)　surface　may　help　reducing　sulfur　poisoning　by　hindering　the　dissociation　of　H2S　molecule.　(C)　2016　Elsevier　B.V.　All　rights　reserved.