Carbon-doped TiO2 nanoparticles in a pure anatase phase colored dark brown were successfully prepared using a convenient controlled nonhydrolytic sol-gel method followed by annealing at 400 degrees C. The UV-Vis diffuse reflectance spectra and X-ray photoelectron spectroscopy (XPS) indicate that substitutional and interstitial carbon atoms coexist in the lattice of TiO2. The shift of photo response of TiO2 from UV to near infrared region is responsible for the multi-type carbon doping by the formation of complex midgap states. The photo-initiated graft polymerization of methyl methacrylate (MMA) is also induced by the carbon impurities in the TiO2 structure. (C) 2007 Elsevier B.V. All rights reserved.