A systematic investigation of Co-Ni-Cu ternary oxide-coated electrodes fabricated by thermal decomposition is performed in alkaline solution by a mixture design approach. Cyclic voltammograms have noticeable differences with the addition of Ni/Cu species into Co3O4 oxide, influencing the corresponding activities of oxygen evolution. The textural results of these oxide electrodes examined by XRD, SEM and XPS demonstrate a spinel structure for all prepared electrodes and a porous morphology with adding Ni/Cu species in the Co3O4 matrix. On the other hand, using mixture experimental design, empirical models for q* : and i fitted and plotted as contour diagrams, facilitate straightforward examinations of the dependence of q* and i on the composition of both binary (Co-Ni, Co-Cu) and ternary (Co-Ni-Cu) oxide systems. The results from contour plots clearly reveal that ternary oxides prepared from the precursors containing 50-63% Co, 30-40% Ni, 5-15% Cu by molar proportion possess the highest electrochemical activity for oxygen evolution.