The　adsorption　and　dissociation　of　methanol　on　Au(111)　surface　were　studied　using　the　first-principles　calculations　based　on　density　functional　theory　(DFT)　with　the　generalized　gradient　approximation　(GGA).　Adsorption　energies,　geometric　structures,　Mulliken　charges　population,　and　vibrational　frequencies　of　the　various　intermediates　were　computed　from　full-geometry　optimization　with　a　three-layer　slab　model.　The　most　stable　adsorption　modes　of　the　species,　i.e.　CH3OH,　CH3O,　and　HCHO　were　considered　in　calculation.　The　possible　decomposition　pathways　were　investigated　with　transition　state　search　methods.　The　results　indicate　that　methoxyl　radical　is　likely　the　decomposition　intermediate.　(c)　2006　Elsevier　B.V.　All　rights　reserved.