The degradation of different commercial reactive dyes: a monoreactive dye (Procion Red H-E7B), an hetero-bireactive dye (Red Cibacron FN-R) and a Standard Trichromatic System, by using solar light assisted Fenton and photo-Fenton reaction is investigated. The reaction efficiencies have been compared with the ones obtained for the same system in the dark or under the assistance of an artificial light source. The use of solar light is clearly beneficial for the removal of color, aromatic compounds (UV254), total organic carbon (TOC), and the increase of the BOD5/COD ratio. The possibility of a combined advanced oxidation process (AOP)/biological treatment based on the use of sunlight is suggested. (C) 2004 Elsevier Ltd. All rights reserved.