Heterogeneous photocatalysis using UV-radiation and TiO2 is an interesting method for the treatment of water polluted with organic substances. In this study, volcanic ashes (VA) and nanostructured titania supported over volcanic ashes (TVA) were used as photocatalysts for dye pollutants photodegradation using methylene blue as model molecule. The impregnation of VA with anatase-type TiO2, was carried out using a hydrothermal method. Natural and supported material samples were characterized by N-2 adsorption-desorption at 77 K. mercury porosimetry, SEM, X-ray diffraction, XPS and UV-vis and IR spectroscopy. The TiO2-nanostructured material displayed good photocatalyst behaviour compared to a commercially used photocatalyst. The effects of type photocatalyst, pH of solution, catalyst amount and adsorption capacity were studied. In addition, the performance of TVA for dye removal under consecutive operation cycles was also investigated. The high photocatalytic activity and the excellent performance under cycling operation displayed by TVA system make it a good candidate to be considered in engineering applications. (C) 2010 Elsevier B.V. All rights reserved.