In this investigation, the effectiveness of using photocatalytic sol-gel TiO2 thin film to decolorize anthraquinonic dye Acid Blue 80 was evaluated experimentally. The TiO2 photocatalysts synthesized were characterized by DSC-TG, XRD, HRTEM, UV-vis spectra, SEM, and XPS. The experimental results showed that a TiO2 thin film formed without high temperature calcination could effectively perform photocatalytic decolorization under UVA irradiation. After the TiO2 thin film was modified by Cr ion implantation, the characterization by UV-vis spectra showed that the light absorption was extended beyond UV to the visible range. The modified thin film could perform visible-light-assisted photocatalytic decolorization of the dye. The overall study demonstrates the promise of solar photocatalytic decolorization of dye for treatment of textile effluent. By adopting immobilized TiO2 thin films instead of conventional suspended TiO2 particles, the photocatalytic water treatment method becomes more cost-effective as the costly filtration process, normally needed to recover TiO2 particles from the effluent discharge, can be omitted. (c) 2006 Elsevier B.V. All rights reserved.