Manganese-complexes of a new series of tetraarylporphyrins, featuring both chlorine atoms in ortho, ortho' positions and N-mono- or N,N-disubstituted sulphonamido groups in meta on the meso-phenyls, were used as catalysts in the epoxidation of alpha-olefines in the presence of diluted (17.5%) H2O2 as primary oxidant. The catalytic efficiency of these catalysts is related to the polarity of the chains and the N, N-dialkylsulphonamido porphyrins turned out to be more reactive than the robust Mn-TDClPP in the epoxidations of styrenes.