Some nitrogen donors, acetate and bromide ions were used as co-catalyst in the epoxidation reaction of cis-stilbene by meta-chloroperbenzoic acid catalyzed by chloro(tetramesitylporphyrinato)manganese(III). Cyclic voltammetry was used for comparison of coordination ability of these axial ligands. Stability of manganese porphyrin complex and lifetime of Mn-oxo intermediate species were compared using UV-vis spectroscopy in the presence of these axial ligands. It was shown that increasing coordination ability of these axial ligands has positive effects on the stability of the catalyst and also on the stability of Mn-oxo intermediate species but has a negative effect on the catalytic activity of the manganese porphyrin complex. (C) 2013 Elsevier B.V. All rights reserved.