The photocatalytic degradation of sulfanilamide, sulfacetamide, sulfathiazole, sulfamethoxazole and sulfadiazine in aqueous solutions was examined during their irradiation with UV-A (366 nm) with TiO2, Fe salts and TiO2/FeCl3 catalysts. The study was carried out by HPLC-UV, HPLC/MS-El and total organic carbon (TOC) methods. It was found that sulfonamides underwent photocatalytic degradation in the presence of TiO2, TiO2/FeCl3 and Fe3+ salts, and the optimum catalyst for this process can be FeCl3. Based on the identified intermediate products, a degradation pathway was proposed. Moreover, the rate of photocatalytic process carried out with FeCl3 as well as the relationship between the pH of irradiated solutions, initial concentrations of sulfanilamide and FeCl3 were stated. (C) 2009 Elsevier B.V. All rights reserved.