Nanocrystalline　Bi2Sn2O7,　a　visible-light　photocatalyst　synthesized　via　a　facile　hydrothermal　route,　is　used　to　remove　arsenite　from　aqueous　solution　for　the　first　time.　The　as-synthesized　Bi2Sn2O7　product　is　characterized　by　X-ray　diffraction,　N-2　sorption-desorption,　UV-vis　diffuse　reflectance　spectroscopy,　transmission　electron　microscopy,　electron　spin　resonance.　X-ray　photoelectron　spectra,　and　electrochemistry　technology.　The　results　reveal　that　the　sample　has　an　average　particle　size　of　approximately　10　nm,　a　specific　surface　area　of　51.3　m(2)/g,　and　a　band　gap　of　2.88　eV.　Moreover,　the　Bi2Sn2O7　nanoparticles　exhibit　a　high　photocatalytic　activity　in　the　oxidation　of　As(III)　(up　to　96.8%)　under　visible-light　irradiation.　center　dot　O-2(-)　and　h(+)　are　recognized　as　the　primary　active　species　responsible　for　As(III)　oxidation.　Meanwhile,　a　possible　mechanism　for　the　photo-oxidation　of　As(III)　over　Bi2Sn2O7　is　also　proposed.　(C)　2012　Elsevier　B.V.　All　rights　reserved.