O-2 activation under mild conditions remains a weighty challenge for chemists. Herein we report a study of electrochemical O-2 reductive activation catalyzed by Fe-III(F20TPP)Cl, by means of cyclic voltammetry and UV-vis spectroelectrochemistry in acidic solutions of N,N-dimethylformamide. Two parallel catalytic pathways have been evidenced occurring at different overpotentials. At high overpotential a classical electron-proton (EPT) pathway where protonation of Fe peroxo ultimately leads to the formation of high-valent Fe oxo species dominates. At low overpotential a proton-electron (PET) pathway involving a hydrosuperoxo species has been identified.