Thin coatings of titania and titania/silica were deposited onto aluminium and anodised aluminum substrates from an aqueous precursor. The titania precursor sol was prepared using a proprietary method, and applied onto cleaned or polished substrates by spray coating. Two-stage heat processing at 160 and up to 650 degreesC densified and crystallised the film. Crack-free, transparent coatings up to 1.00 mum thick can be produced from a single application using this precursor system. X-ray diffraction was used to identify the crystal phase of the films as anatase, and resonant nuclear reaction (RNRA) experiments were carried out to assess the degree of aluminium migration from the aluminium substrates into the films. Photocatalytic oxidation of an organic dye on the surface was monitored by a novel fluorescence method. Water droplet contact angles were measured on the film surfaces before and after UV illumination to investigate the photoactivated hydrophilicity of the films. The activities were compared with films prepared on glass and ceramic substrates. (C) 2003 Elsevier B.V. All rights reserved.