Hydrothermal and reflux synthesis methods were utilized for the preparation of 5% Sn doped TiO2 nanopowders. Obtained powders were subjected to particle size and specific surface area measurements, flame atomic absorption spectroscopy, X-ray diffraction analyses and transmission electron microscopy examination. TiO2 powder prepared by hydrothermal synthesis presented a bimodal particle size distribution with average particle sizes of about 3 and 10 nm, whereas TiO2 powder synthesized by reflux method had an average particle size of 7 nm. Specific surface areas of hydrothermal and reflux synthesized TiO2 were 130 and 115 m(2)/g, respectively. Sn doping in TiO2 was 95.8% in hydrothermal and 86.4% in reflux synthesis as measured by FAAS, respectively. Photocatalytic activities of the obtained TiO2 powders were evaluated by decomposition of malachite green solution in a solar box. Photocatalytic activity of hydrothermally synthesized TiO2 was fairly higher in visible light and slightly higher in UV light than the activity of reflux synthesized TiO2.