Bi-doped TiO2 catalyst was prepared by sol-gel method and was characterized by thermo gravimetric analysis (TGA), X-ray diffraction spectra (XRD), X-ray photo electronic spectroscopy (XPS). UV-Vis diffused reflectance spectra (DRS), photoluminescence spectra (PLS), transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDAX) and BET surface area. The photocatalytic activity of the catalysts were evaluated for the degradation of isoproturon herbicide under solar light irradiation. The UV-Visible DRS of Bi-doped TiO2 showed red shift in optical absorption. The presence of Bi3+delta+ species are playing a vital role in minimizing the electron hole recombination resulting higher activity compared to bare TiO2. (C) 2011 Elsevier Ltd. All rights reserved.