Transition metal-iodosylarene complexes have been proposed to be key intermediates in the catalytic cycles of metal catalysts with iodosylarene. We report the first X-ray crystal structure and spectroscopic characterization of a mononuclear nonheme manganese-(III)-iodosylarene complex with a tetradentate macro cyclic ligand, [Mn-III(TBDAP)(OIPh)(OH)](2+) (2). The manganese(III) iodosylarene complex is capable of conducting various oxidation reactions with organic substrates, such as C-H bond activation, sulfoxidation and epoxidation. Kinetic studies including isotope labeling experiments and Hammett correlation demonstrate the electrophilic character on the Mn-iodosylarene adduct. This novel intermediate would be prominently valuable for expanding the chemistry of transition metal catalysts.