The nanoparticles of TiO 2 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 TiO 2 to shift the visible light region. Fe(III) cation could be doped into the matrix of TiO 2 , by which could hinder the recombination rate of excited electrons/holes. Superior photocatalytic activity of TiO 2 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 TiO 2 nanoparticles were responsible for improving visible light photocatalytic activity.