Titanium dioxide thin films were deposited by DC reactive magnetron sputtering and spray pyrolysis methods on glass and glass coated with fluorine tin oxide (FTO). The films were characterized by X-ray diffraction, scanning and transmission electron microscopy, atomic force microscopy and UV-vis spectroscopy. The influence of a reactive atmosphere: a 50/50 Ar-O2 mixture on TiO2 thin films deposited by sputtering has been studied following the evolution of surface and structural properties and has been correlated, when possible, with photocatalytic properties under UV illumination. Also transparent TiO2 thin films have been prepared by spray pyrolysis using a low concentration of titanium precursor and different substrates temperatures. At higher substrate temperatures the films were polycrystalline in anatase phase; at lower substrate temperatures the films presented amorphous configuration. The best photocatalytic activity was found for films deposited by spray pyrolysis at Ts = 450°C and for those deposited by magnetron sputtering those deposited at 16 mTorr gave the higher photodegradation rates. © 2004 Elsevier B.V. All rights reserved.