Carbon-modified (CM)-n-TiO2 films of different carbon contents were synthesized by spray pyrolysis of glucose containing TiCl4 solution. The resulting films exhibit significant dependence of photocurrent on their carbon contents; the increase in the carbon doping enhanced the photoresponse of n-TiO2 films. It was found that carbon doping reduced the bandgap energy of TiO2 from 3.2 to 2.78 eV and created a new energy band which lies 1.45 eV above the valence band. These bandgap modifications of n-TiO2 extended the utilization of solar energy up to the visible region, leading to the enhancement in the photoresponse of CM-n-TiO2. (c) 2007 The Electrochemical Society.