When titania (TiO2) is doped with a nommetallic element such as sulphur and nitrogen, it exhibits visible-light photocatalytic reactivity. However, it is not always easy to carry out the doping operation. The authors have developed a new method for doping the nonmetallic element into a TiO 2 sample by its grinding with sulphur/nitrogen-containing materials, followed by calcination at low temperature. This is called mechnaochemical doping, which allows the TiO2 sample to possess two absorption edges around 400 and 540 nm in visible light of wavelength. Under irradiation of the visible light of wavelength over 510 nm, it has been confirmed that the sample of TiO2 doped with sulphur/nitrogen has shown excellent photocatalytic ability for nitrogen monoxide destruction.