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.