We have synthesized a carbon doped titanium oxide powder (C-TiO2) which is a photo-catalytic material acting under irradiation of light of wave length in visible region, by mechanochemical (MC) and heating operations. The MC operation is conducted by grinding TiO2 with ethanol (C2H5OH) in air, and the heating is carried out at different temperatures in air. The prepared samples were characterized by a series of analytical methods including X-ray diffraction, thermogravimetry-mass spectroscopy, Fourier transform infrared spectroscopy, specific surface area measurement, X-ray photoelectron spectroscopy (XPS), NOx gas decomposition and ultraviolet visible spectroscopy (UV-vis). XPS analysis particularly demonstrates the existence of C-Ti and C-O bindings, to which the improvement in photo-catalyst is attributed. (C) 2007 Elsevier B.V. All rights reserved.