A　series　of　CdS　nanowire-Au　nanocomposites　(CdS　NW-Au　NCs)　with　different　weight　addition　ratios　of　Au　nanoparticles　(NPs)　are　successfully　synthesized　by　using　a　simple　and　efficient　electrostatic　self-assembly　method　at　room　temperature　for　utilizing　the　natural　surface　charge　properties　of　the　CdS　NWs　and　Au　NPs.　These　natural　surface　charge　properties　are　dependent　on　the　synthesis　approaches.　The　probe　reactions　for　photocatalytic　selective　reduction　of　nitroaromatic　compounds　in　the　aqueous　phase　under　visible　light　irradiation　are　utilized　to　evaluate　the　photoactivity　of　this　series　of　as-prepared　CdS　NW-Au　NCs.　The　CdS　NW-Au　NCs　exhibit　significantly　enhanced　photoactivity　as　compared　to　the　CdS　nanowires　(CdS　NWs).　The　addition　of　Au　NPs　into　the　CdS　NW　domain　enables　efficient　enhancement　of　the　lifetime　and　transfer　of　photogenerated　charge　carriers　from　CdS　NWs　under　visible　light　irradiation.　However,　the　addition　of　excess　amounts　of　Au　NPs　not　only　influences　the　penetration　of　light　but　the　Au　NPs　also　become　the　recombination　centers,　and　result　in　decreased　photoactivity.　The　optimal　proportion　of　the　Au　NPs　is　proved　to　be　1　wt%,　which　indicates　the　synergistic　effect　between　the　CdS　NWs　and　Au　NPs.　In　addition,　the　surface　plasmon　resonance　(SPR)　effect　of　Au　NPs　is　proved　to　not　play　an　efficient　role　in　the　reaction　and　the　possible　photocatalytic　reaction　mechanism　is　proposed.　It　is　hoped　that　this　work　could　aid　in　the　fabrication　of　1-D　semiconductor-metal　nanocomposites　by　using　such　a　simple　and　efficient　electrostatic　self-assembly　strategy.　In　addition,　it　is　also　expected　to　enrich　and　supplement　their　application　as　visible　light　photocatalysts　toward　selective　organic　transformations　through　our　investigation.　©　The　Royal　Society　of　Chemistry　2013.