The anatase nanoparticulate TiO2 films were calcined at temperatures ranging from 500 degrees C to 650 degrees C under nitrogen and ammonia atmospheres, respectively. The bare and calcined films were characterized by Raman spectroscopy, atomic force microscope, ultraviolet-visible absorption spectroscopy and X-ray photoelectron spectroscopy. The photocatalytic activities were evaluated by studying the decomposition of methylene blue. With the same crystalline phases and same N dopant concentrations, the films calcined in NH3 exhibited much larger redshifts of the photoabsorption edges and much higher visible-light photocatalytic efficiencies than the films calcined in N-2, indicating the incorporation of hydrogen played an important role in the bandgap narrowing. (C) 2008 Elsevier B.V. All rights reserved.