Biomimetic catalysts such as metalloporphyrins, which can yield highly oxidized metallo-oxo species, have been used as lignin peroxidase models. However, natural porphyrins are unstable under catalytic oxidation conditions due to their self-destruction or to the formation of inactive mu-oxo complexes. An alternative approach to the preparation of robust catalysts consists in the immobilization of metalloporphyrins on supports that mimic the polypeptide envelope, which protects the catalytic center of natural enzymes. We report here the use of manganese meso-tetrakis(tetramethylpyridinio)porphyrin pentaacetate immobilized on the smectite clay montmorillonite as a suprabiotic catalyst for the oxidation of lignin model compounds. (C) 2003 Elsevier B.V. All rights reserved.