A kinetic model of oxygen reduction at an inert electrode in a carbonate melt has been proposed. Combined with the thermodynamic calculations of the chemical equilibria in the carbonate melts and with the diffusivity values taken from the literature, the model was used to simulate kinetics of oxygen reduction reaction at a gold electrode in the Li2CO3 / K2CO3 (62 / 38mol %) molten electrolyte under 0.33 О2 +0.67 СО2 atmosphere at 923K for the case of coulostatic pulse perturbation. The simulation has shown that the partial exchange current of the O 2 − reduction step makes the largest contribution to the overall exchange current, and neutralization of the oxide ion by CO2 controls the rate of the overall electrode process. The total exchange current per one-electron electrode reaction was estimated as 83mA/cm2. The simulation has demonstrated satisfactory agreement with the experiment.