The　decomposition　of　an　environmentally　recalcitrant　s-triazine　compound,　prometry　(PMT),　was　carried　out　by　experimental　and　theoretical　approaches　to　study　the　combined　effects　of　hydroxyl　radicals　(center　dot　OH)　and　hydrated　electrons　(e(aq)(-)).　With　the　participation　of　strongly　oxidative　radicals　(OH)-O-center　dot　and　reductive　radicals　e(aq)(-)　induced　by　electron　beam　(EB),　PMT　obtained　a　good　decomposition　performance,　which　was　obviously　better　than　those　methods　simply　using　(OH)-O-center　dot　as　the　single　active　species.　The　evolution　of　cyanuric　acid　(CA)　during　the　EB　and　UV　irradiation　processes　elucidate　that　former　method　could　efficiently　decompose　such　chemically　stable　intermediate.　The　experiments　of　radical　scavengers　further　suggest　that　(OH)-O-center　dot　was　the　predominant　radical　during　PMT　degradation,　while　e(aq)(-)　was　beneficial　to　further　decomposition　and　mineralization.　Combined　with　the　results　of　density　functional　theory　(DFT)　calculations,　the　strengthened　synergistic　effects　between　(OH)-O-center　dot　and　e(aq)(-)　were　proven.　The　calculations　illustrated　(OH)-O-center　dot　could　attack　the　carbon-branch-chains　of　s-trazine　ring　and　form　OH-adducts　rather　than　nitrogen　oxides.　Moreover,　the　presence　of　e(aq)(-)　could　not　only　greatly　change　the　geometry　of　the　s-triazine　ring,　but　also　help　cleaving　alkyl　chain　on　ring,　thus　facilitate　the　complete　mineralization.　(C)　2017　Elsevier　Ltd.　All　rights　reserved.