The catalytic oxidation of 2,4,6-trichlorophenol (TCP) by a homogeneous Fe-porphyrin catalyst (FeR4P) and the corresponding heterogeneous one (immobilized on silica, FeR4P-SiO2) was studied by analytical and EPR spectroscopic methods. The homogeneous catalyst was found to be more efficient for oxidative decomposition and dechlorination of TCP, compared to the heterogeneous FeR4P-SiO2 catalyst. The main, initial and final, oxidation products were identified and a general catalytic mechanism was proposed concerning TCP oxidation and the by-products formation, in relation with the catalyst's redox cycle. (C) 2010 Elsevier B.V. All rights reserved.