Molten carbonate fuel cells (MCFCs) have attracted significant attention because of their potential contribution to the development of a sustainable and clean-energy society. MCFC performance is governed by cathodic transformation of carbon dioxide to carbonate anion in complex: gas molten carbonate solid surface system. Based on our recently proposed reaction mechanism together with the density functional theory (DFT) calculated activation barriers we created a simplified microkinetic model to predict the catalytic activity of the NiO cathode. Under the MCFC operation condition the cathode surface in close proximity to the triple phase boundary (TPB) is highly active towards electro-reduction of oxygen and simultaneous formation of carbonate anion. Our results explain why, despite a great effort devoted to modify the chemical composition of the cathode, a substantial increase in the MCFC performance has not been observed, and the in-situ oxidized nickel remains state-of-the-art cathode material.