The unique phase composition beta-Sn1-nWO4.n alpha-Sn, including nanoscale incipient crystalline beta-SnWO4 and alpha-Sn, turned out to be a very promising photocatalyst under simulated daylight. Since the nanomaterial is gained via a quick and simple precipitation in water without using toxic elements or solvents, the synthesis can be regarded as real "green". Despite its simple preparation, the nanoparticles are of high quality, exhibiting an average diameter of 20 nm, a low degree of agglomeration, a high specific surface (71 m(2) g(-1)) and an efficient electrostatic stabilization (zeta <-40 mV at pH = 3.5-9.5). As-prepared [beta-Sn1-xWO4.n alpha-Sn exhibits a strong absorption in the visible spectral range (554 nm, 2.2 eV) and a lasting high photocatalytic performance under simulated daylight. Various organic dyes (phenothiazine dye methylene blue, triphenylmethane dye basic green 4, azo-dye methyl red) are decomposed with significantly higher degradation rates (5-10) as compared to commercially available Degussa P25 (TiO2, 80% anatase, 20% rutile). Recycling experiments prove the phase stability and reusability of as-prepared beta-Sn1-nWO4.n alpha-Sn. (C) 2010 Elsevier B.V. All rights reserved.