A　simply　as-prepared　nickel　phosphotungstate　complex　was　used　as　a　carbon-free　homogeneous　catalyst　for　the　H2　evolution　from　water　splitting　under　visible　light　irradiation　(λ　≥　400　nm).　Its　catalytic　activity,　the　rate　of　the　H2　evolution　about　237　μmol　h-1,　was　much　higher　than　those　of　the　Ni2+　ions　and　cobalt　phosphotungstate　complex.　Spectroscopic　studies　suggested　that　the　Ni2+　ions　could　react　with　Na8HPW9O34　to　form　a　complex　with　a　unique　double-sandwich　structure　in　the　as-prepared　sample.　And　the　electrochemical　experimental　results　revealed　that　it　possessed　two　satisfactory　redox　potentials,　which　were　in　favor　of　the　electrons　transfer　in　our　photoinduced　hydrogen　production　system.　Furthermore,　the　electron-transfer　steps　for　the　H2　evolution　from　water　splitting　in　the　present　system　were　investigated　in　detail.　On　the　basis　of　the　luminescence　analysis　results,　it　was　found　that　the　reductive　quenching　pathway　was　dominant　for　the　photosensitizer　in　the　present　system.　©　2015　Hydrogen　Energy　Publications,　LLC.