AbstractOxygen reduction reaction (ORR) has been disclosed in recent studies as a significant secondary cathodic process during magnesium corrosion. This work elaborates on the contribution of ORR to the total corrosion process of pure Mg at different impurity levels in NaCl electrolyte with the assistance of local techniques. A finite element based numerical model taking into account the contribution of ORR during the corrosion of the Mg test materials has been designed in this study considering the local oxygen concentration. Respective computational simulations were calibrated based on the experimental data and evaluated accordingly. Finally, the simultaneous monitoring of local concentration of H2 and O2, and the combined modeling study reveal the relation between ORR and hydrogen evolution reaction.