Molecular oxygen was investigated as sustainable oxidant for the degradation of LAS (linear alkylbenzenesulphonic acids) in the presence of homogeneous and heterogeneous iron based catalysts. The influence of temperature, oxygen pressure and substrate/catalyst molar ratio on the degree of mineralization and LAS conversion was considered. Molecular oxygen showed an interesting behaviour as selective oxidant: the conversion to CO2 was low in all cases and the formation of useful partial oxidation products was observed. The applicability of the process to convert a waste product in fine chemicals was evaluated. (C) 2004 Elsevier B.V. All rights reserved.