Mesoporous thin titanium dioxide films have been prepared on titanium plates through micro-plasma oxidation. To increase the films' photocatalytic activity, La ions with different concentrations (0, 0.025, 0.005, 0.075, 0.1 g/L) were added into the H2SO4 electrolyte solution. X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy techniques were applied to characterize the modified films. A kind of typical textile industry pollutant (Rhodamine B) was used to evaluate the photo-catalytic activity of the films. The results showed that this activity of the films had been improved by adding La ions into the electrolyte solution. The enhanced photo-catalytic activities might be resulted from the increase of mesopores' number, producing more reactive sites to absorb and oxidize pollutants. Also, the improvement was related to the forming of titanium dioxide lattice distortion, which could accept more photoexcitated holes and produce more strong surface free radicals to oxidate adsorptive molecules. (c) 2006 Elsevier B.V. All rights reserved.