Carbon wrapped and doped mesoporous anatase TiO2 nanocrystals were prepared by a hydrothermal approach in acetic acid aqueous containing chitosan. A designed post-thermal treatment was employed to enhance the incorporation between carbon and TiO2. After hydrothermal process, mesoporous anatase TiO2 formed with wrapped by a few layers of carbon shell. Here chitosan was used as not only the template for the formation of mesopores, but also the carbon source toward the carbon layers coating. Furthermore, chitosan provided doping element into TiO2 lattice and induced to form Ti-C bond which caused Ti(III) with oxygen vacancies. The Ti(III)-oxygen vacancy are partly responsible for visible-light response and high photocatalytic activity, which can accelerate electron transfer thus inhibit photogenerated charge recombination. The photocatalytic activity was evaluated using photo-oxidation of gaseous NO under visible light irradiation as the probe reaction. In the optimum result, 71% of NO with starting concentration at ppb level was photo-degraded. Our results also showed that the photogenerated electrons played a key role in photodegradation of NO, as a result, the environmental humidity level had a negligible effect on the photocatalysis. (C) 2016 Elsevier B.V. All rights reserved.