The importance of transition metal oxides in electrocatalysis is well known. The electrocatalytical results can be attributed to both cationic composition of the oxide and electrode manufacturing. In order to study separately the surface area effects and the intrinsic catalytic nature, Cu1+xMn2-xO4(1.4 greater than or equal to 1 + x greater than or equal to 1) spinel oxides were synthesized by two different ways : spray pyrolysis and, thermal decomposition of metallic salts. The oxides obtained were characterized by means of X-ray diffraction (XRD), electrical conductivity and pzc (pH of zero charge) measurements. Five types of electrodes were obtained from the electrocatalytic candidate material. Their electrochemically accessible surface area (easa) was determined using Zn2+ adsorption and kinetic measurements of a simple redox couple; results of which were in good agreement. The electrocatalytical activity of electrode materials was evaluated studying the oer (oxygen evolution reaction) in 1M KOH. The activity was found to be dependent of the surface area effects and (Mn3+ + Mn4+) ions stoichiometry (octahedrally co-ordinated with oxygen atoms in spinel structure). The possibility that information about the structure of the bulk oxide can be extrapolated to the surface is emphasized.