The photocatalytic mineralization of methanol, ethanol and I-propanol is compared with those of their homologous carboxylic acids (formic, acetic and propanoic). The presence of S2O82- ions almost does not affect the alcohols mineralization. But, those of the acids are slowed down. In addition to this, adding H2O2 inhibits the alcohols mineralization and those of the acids, but to a lesser extent. FT-IR studies have shown that carboxylates generated from the oxidation of the corresponding alcohols adsorb at different centres from those where carboxylates directly generated from formic, acetic and propanoic acids do. From the obtained results, mineralizations of these compounds have been correlated with their proximity and accessibility to photoactive centres. (c) 2005 Elsevier B.V. All rights reserved.