While carbon-based cathodes normally provide MgCO3 as the end discharge result, Mo2C-CNT cathodes can trigger MgC2O4 nucleation in the early stages of battery discharge, as shown by experimental findings from non-aqueous Mg-CO2 battery investigation. However, earlier experimental studies have failed to definitely identify the ultimate discharge product in Mg-CO2 batteries. We have chosen MgC2O4 and MgCO3 nucleation as the focus of our investigation on discharge products to acquire a more in-depth understanding of the reaction mechanisms occurring on the investigated RuO2 (211) surface. We studied both the open circuit (U= 0 V) and equilibrium potential (Uo (MgC2O4) = 1.98 V and Uo (MgCO3) = 2.13 V) Gibbs free energies of the intermediates involved in the nucleation of MgC2O4 and MgCO3 to understand more about the catalyst's efficiency in this regard. The non-aqueous Mg-CO2 batteries demonstrate an inherent propensity to adhere to a four-electron pathway, which comprises of four elementary steps within diffusion cathodes. Overall, the lowest rate-determining step for MgCO3 and MgC2O4 nucleations are found to be path VI and path IV, making them the most viable pathways for MgCO3/MgC2O4 nucleations (See Figure ). Furthermore, when equilibrium potentials are employed, the variations in free energy for MgCO3 and MgC2O4 nucleation are -0.631 eV and -1.736 eV, respectively. The free energy changes of the rate-governing steps at equilibrium potentials were calculated to determine the overpotentials for nucleation of MgCO3 and MgC2O4 on the studied RuO2 (211) surface, according to η0 = -∆Gf / (n.e). The data presented in Table and Figure indicate that the overpotential for the free energy change of MgC2O4 nucleation is significantly lower (0.063 V) than that of MgCO3 (0.67 V), confirming that the nucleation of MgC2O4 as a discharge product using RuO2 (211) cathode catalyst is thermodynamically favorable in the overall reaction process for Mg-CO2 batteries.