Mesoporous titanium dioxide films were fabricated on titanium plates by micro-arc oxidation method.To increase the photocatalytic activity of the films,NH4NO3 was added to the H2SO4 solution,and anodizing was carried out at high voltages using a DC power supply.The crystal structure,chemical composition,surface morphology and the optical property of the films were investigated by XPS,XRD,UV-VIS spectroscopy and SEM.The photocatalytic activity of the films was evaluated by the decomposition of aniline blue,and the activity of the films for the degradation turned out to be improved by the additives to the electrolyte solution.The enhanced photocatalytic activity might result from the increased porosity and nitrate ion incorporation into the anodic films by micro arcing,and thereby the TiO2 layer might exhibit an improved absorption property for the visible light. Mesoporous titanium dioxide films were prepared on titanium plates by micro-arc oxidation method. To increase the photocatalytic activity of the films, NH4NO3 was added to the H2SO4 solution, and anodizing was carried out at high voltages using a DC power supply. The crystal structure , chemical composition, surface morphology and the optical property of the films were investigated by XPS, XRD, UV-VIS spectroscopy and SEM. The photocatalytic activity of the films was evaluated by the decomposition of aniline blue, and the activity of the films for the degradation turned out to be improved by the additives to the electrolyte solution. The enhanced photocatalytic activity might result from the increased porosity and nitrate ion incorporation into the anodic films by micro arcing, and thus the TiO2 layer might exhibit an improved absorption property for the visible light.