A new Mn-porphyrin bearing four pyridinium substituents bound through their nitrogen atoms on the meso-positions of the tetrapyrrole ring was synthesized in three steps from Zn-beta-octaethylporphyrin. It was characterized by elemental analysis, electrospray mass spectrometry, UV-vis and dual polarization mode EPR spectroscopy, and electrochemistry. Electrochemical and EPR studies showed that the Mn-porphyrin prepared by this method existed as a 80/20 Mn(II)/Mn(III) mixture, the redox potential of the Mn(III)/Mn(II) couple being +345 mV (versus SCE, in CH3CN). It catalyzed alkene epoxidation and alkane hydroxylation by PhIO with characteristics comparable to those of Mn[TDCPP=meso-tetra-(2,6dichlorophenyl)porphyrin]Cl. It also catalyzed the hydroxylation of anisole, naphthalene and ethylbenzene by H2O2 in CH2Cl2/CH3CN, as well as the hydroxylation of the drug diclofenac by oxone in water. It is a new biomimetic catalyst exhibiting two distinctive characteristics: a good solubility in both hydrophobic aprotic solvents and water for pH > 5, and an unusual structure with four positive charges very close to the metallic centre. (c) 2006 Elsevier B.V. All rights reserved.