The photocatalytic degradation of Auramine O, a diarylmethane fluorescent dye, has been investigated in aqueous heterogeneous solutions containing semiconductor oxides as photocatalysts. The disappearance of the organic molecule follows approximately a pseudo-first order kinetics according to the Langmuir-Hinshelwood model. CO2 and NH4+ ions have been identified as mineralization products. Various commercial photocatalysts are compared with respect to their decolorization efficiency, as well as the production of CO2. The effect of pH and H2O2 on the reaction rate is ascertained.