The oxygen evolution process on NiCo2-xRhxO4 (0 less than or equal to x less than or equal to 0.5) spinel system was studied in 5 mol dm(-3) KOH aqueous solution at room temperature. The electrodes electrocatalytical activity was analysed in terms of Tafel slope, exchange current density and overpotential values. The experimental results show that the performance of the electrodes is significantly improved by the presence of rhodium, mainly due to the increase of surface and electroactive areas.