This　work　focuses　on　the　nature　of　enhanced　H2　production　over　SnO2/TiO2　composite　photocatalysts.　Three　kinds　of　Sn-modified　TiO2　materials　were　prepared　by　different　methods.　Photocatalytic　H2　production　from　methanol/water　solution　as　a　model　reaction　was　used　to　evaluate　the　photocatalytic　properties　of　the　materials.　The　chemical　states　of　Sn　were　characterized　in　detail　by　transmission　electron　microscopy,　X-ray　photoelectron　spectroscopy,　and　X-ray　absorption　fine　structure　spectroscopy.　The　results　reveal　a　Sn　nuclearity-dependent　enhancement　of　H2　production　over　Sn/TiO2　photocatalysts.　According　to　the　characterization　results,　it　was　well　established　that　the　number　of　TiIV-O-SnIV　linkages　formed　at　the　TiO2-　SnO2　interface　determines　the　enhancement　amplitude　of　H2　production.　The　photogenerated　electrons　of　TiO2　across　the　interfacial　linkages　are　transferred　into　the　mononuclear　Sn　moieties　grafted　on　the　(1　0　1)　and　(0　0　1)　planes,　where　H2　is　presumably　released.　An　interatomic　electron　transfer　pathway　for　accelerating　photocatalytic　H　2　production　over　Sn/TiO2　catalysts　was　proposed　based　on　this　work.　©　2012　Elsevier　Inc.　All　rights　reserved.