The photocatalytic degradation of Cibacron Yellow LS-R (CIY), an azo dye, has been investigated in aqueous heterogeneous solutions containing semiconductor oxides as photocatalysts. The disappearance of the organic molecule follows approximately a pseudo-first kinetic order according to the Langmuir-Hinshelwood model. Various commercial photocatalysts are compared with respect to their decolorization efficiency, the COD, as well as the toxicity reduction. The effect of the temperature on the reaction rate is ascertained. (C) 2007 Elsevier B.V. All rights reserved.