Catalytic activity and oxidative stability of a series of Mn-porphyrins (Mn-pots) with pyridyl (2-, 3- or 4-), 4-sulfonatophenyl, 3-sulfonato-4-methoxyphenyl, phenyl and 4-methoxyphenyl in oxidation of olefins with tetra-n-butylammonium periodate has been investigated in a comparative study. While the complexes with pyridyl substituents, MnT(py)P(OAc) are generally more stable than those with the other aryl groups toward oxidative degradation in reaction conditions, their catalytic activity is usually lower than these Mn-pors. MnT(4-py)P(OAc) was found to be unusually more stable than MnT(2- or 3-py)P(OAc). The order of catalytic performance of the used Mn-pors and their oxidative stability are less correlated with the electronic properties of the meso substituents. On the basis of indirect evidence obtained in competition oxidation of cis- and trans-stilbene, the involvement of a six coordinate (IO4)Mn(III)(Porphyrin)(ImH) and a high valent Mn-oxo species has been proposed. However, in the case of MnT(py)P(OAc), the latter seems to be more dominant than the former. (c) 2012 Elsevier B.V. All rights reserved.