Correlations between solid state chemistry, surface properties and electrocatalytical reactivities towards the reaction of oxygen are investigated on powder electrodes of cobalt and manganese spinel type oxides MnxCo3-xO4 (0 less than or equal to x less than or equal to 1). The cationic distributions have been computed from X-ray diffractometry, magnetism and oxidation power:data, showing the occurrence of the Mn4+/Mn3+ solid state redox couple in octahedral sites. The change of the Mn4+/Mn3+ content as a function of x have been correlated to pH of zero charge, pH(z), rest potential, E-i=0, activation-energy of conductance, E-a, and to the electrocatalytical parameters of the oxygen reduction reaction (ORR) and evolution reaction (OER). Manganese catalyzes the ORR but inhibits the OER.