Solar photodegradation of two commercial surfactants, SDS and DBS, has been studied in this work. Laboratory scale experiments showed that photo-Fenton reaction was the most effective method, although results were also very satisfactory using titanium dioxide as photocatalyst. In the photo-Fenton process, it was possible to use Fe(H) and Fe(III) cations, as well as Cr(III); the last possibility could be interesting in the case of wastewaters containing chromium, e.g., those produced by leather related industry. In all cases, it was easier to degrade DBS than SDS. Pilot plant experiments were carried out, and degradation yields higher than 80% were obtained in most of the cases in less than 3 It of exposure to sunlight. The best results were obtained again using iron salts as photocatalysts (photo-Fenton). (C) 2004 Elsevier Ltd. All rights reserved.