Carbon-coated TiO2 photocatalysts were prepared from the powder mixtures of TiO2/PVA of 90/10 in mass at a temperature of 500-1000 degrees C for I h in high pufity nitrogen gas flow. Carbon-coated TiO2 prepared at low temperatures as 600 degrees C, of which carbon content was 5.5 mass%, was shown to be applicable for NO gas oxidation, a little higher activity than the original anatase powder. For the photodecomposition of methylene blue in water, however, the one heated at 800 degrees C showed the highest activity among the samples used, even better than the original anatase without carbon coating. The crystallfinity of anatase phase was shown to be important factor for the application to whether contaminants in water or gaseous ones even in carbon-coated TiO2 photocatalysts. (c) 2005 Elsevier B.V. All rights reserved.