The　new　role　of　graphene　(GR)　in　boosting　the　two-electron　reduction　of　O2　to　H2O2　has　been　first　identified　in　the　GR-WO3　nanorod　(NR)　nanocomposite　photocatalysts,　which　are　fabricated　by　a　facile,　solid　electrostatic　self-assembly　strategy　to　integrate　the　positively　charged　branched　poly(ethylenimine)　(BPEI)-GR　(BGR)　and　negatively　charged　WO3　NRs　at　room　temperature.　Photoactivity　test　shows　that,　as　compared　to　WO3　NRs,　BGR-WO3　NRs　with　an　appropriate　addition　ratio　of　GR　exhibit　remarkably　enhanced　and　stable　visible-light　photoactivity　toward　the　degradation　of　Rhodamine　B.　Besides　the　common　roles　of　GR　observed　in　the　GR-based　composite　photocatalysts　in　the　literature,　including　enhancing　the　visible-light　absorption　intensity,　improving　the　lifetime　and　transfer　of　photogenerated　charge　carriers,　and　increasing　the　adsorption　capacity　for　reactants,　we　have　observed　the　new　role　of　GR　in　boosting　the　two-electron　reduction　of　O2　to　H　2O2　in　this　specific　BGR-WO3　NR　photocatalyst　system.　Importantly,　this　new　role　of　GR　does　contribute　to　the　overall　photoactivity　enhancement　of　BGR-WO3　NR　nanocomposites.　The　synergistic　contribution　of　GR　on　improving　the　photoactivity　of　WO3　NRs　and　the　underlying　reaction　mechanism　have　been　analyzed　by　the　structure-photoactivity　correlation　analysis　and　controlled　experiments　using　radicals　scavengers.　©　2014　American　Chemical　Society.