Thin-layer electrochemistry and steady-state current-potential curves were used to study the electrochemical behavior of the {(TPA)Mn(III)(2)Mn(IV)(TPA)}(2)(SO4)(3) complex in an aqueous medium and forecast its role in a catalytic reaction using the usual oxidants. By studying the concentration and pH effects it is possible to assess the complex’s stability domain, on the one hand, and to characterize the oxidation state of the two manganese atoms and construct a potential-pH diagram including the various equilibria between the manganese species on the other.