The photocatalytic degradation of several aniline derivatives present in aqueous solutions containing TiO₂ suspensions was investigated. The process leads to the complete and fast decomposition (within about 1 h) of the pollutant molecules, promoted by oxidizing radical species formed at the irradiated semiconductor/water interface. The stoichiometric formation of CO₂ from the organic carbon was assessed, whereas other inorganic end-products were detected depending on the nature of the aniline substituents. Unstable hydroxyaromatic intermediates were also identified during the initial steps of the treatment. The primary degradation, which follows pseudo-first-order kinetics, changes with the aniline substituents and is strongly dependent on pH.