The nanoparticles of TiO2 modified with carbon and iron were synthesized by sol-gel followed solvothermal method at low temperature. Its chemical composition and optical absorption were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence emission spectroscopy (PL), UV-vis absorption spectroscopy, and electron paramagnetic resonance (EPR). It was found that carbon and iron modification causes the absorption edge of TiO2 to shift the visible light region. Fe(III) cation could be doped into the matrix of TiO2, by which could hinder the recombination rate of excited electrons/holes. Superior photocatalytic activity of TiO2 modified with carbon and iron was observed for the decomposition of acid orange 7 (AO7) under visible light irradiation. The synergistic effects of carbon and iron in modified TiO2 nanoparticles were responsible for improving visible light photocatalytic activity. (C) 2010 Elsevier B. V. All rights reserved.