Thiophene　adsorption　on　the　Rh(111)　surfaces　has　been　investigated　by　density　functional　theory.　The　results　show　that　the　adsorption　at　the　hollow　and　bridge　sites　is　the　most　stable.　The　molecular　plane　of　the　thiophene　ring　is　distorted,　the　C=C　bond　is　stretched　to　1.448　Å　and　the　C-C　bond　is　shortened　to　1.390　Å.　The　C-H　bonds　tilt　22∼42°　away　from　the　surface.　The　calculated　adsorption　geometries　are　in　reasonable　agreement　with　population　analysis　and　density　of　states.　The　thiophene　molecule　obtains　0.74　electrons　reflecting　the　interaction　between　the　lone　pair　of　sulfur　and　the　d-orbitals　of　metal.　The　reaction　paths　and　transition　states　for　desulfurization　of　the　molecule　have　been　investigated.　The　bridge　adsorption　structure　of　thiophene　leads　to　a　thiol　via　an　activated　reaction　with　an　energetic　barrier　of　0.30　eV.　This　second　step　is　slightly　difficult,　and　dissociation　into　a　C4H4　fragment　and　a　sulfur　atom　is　possible,　with　an　energetic　barrier　of　0.40　eV.