For non-aqueous Mg-CO2 batteries, experimental studies using Mo2C-CNT cathodes have reported the formation of MgC2O4, MgCO3, MgO, and C. Using ex-situ Raman spectroscopy, Liu et al. identified signature peaks at 1060, 1132, and 1200 cm -1 that ascribe to MgO, MgCO3, and MgC2O4, respectively, as well as carbon (D peak at 1348 cm -1 and G peak at 1576 cm -1 ) and Mg. When a carbon nanotube (CNT) cathode was used, however, the Raman and FTIR spectra reported by Zhang et al. only showed the existence of MgCO3 and C as discharge products. The final discharge product in metal-CO2 batteries has been a subject of ambiguity in previous experimental and theoretical studies. We propose three key mechanisms to initiate reactions that lead to the formation of the final discharge products in Mg-CO2 batteries: (i) selective absorption of Mg atoms at catalytic sites, followed by CO2 absorption, (ii) CO2 absorption followed by Mg absorption, and (iii) two consecutive CO2 absorptions. Figure depicts the suggested routes of the overall reaction process. The reaction pathways rely on the interplay between CO2, Mg, and the catalytic surfaces. The stabilization of MgC2O4 has been observed to have a positive impact on reducing the oxidative decomposition barrier in alkali metal-CO2 batteries. In the pathways studied, Mg or CO2 initially adsorbs onto the catalytically active site. The specific adsorbed MgCO2 species (MgCO2*) formed during this adsorption process is determined by the binding sequences of Mg and CO2 on the catalytic surface (Pathways I, IV, V, and VI). Two CO2 species can co-adsorb via chemical dimerization, leading to the formation of carbonate species (CO3* and CO* (Path II)) or oxalate (C2O4 2-(Path III)). MgC2O4 nucleation occurs on the catalyst surface as a result of the oxalate species reacting with Mg. Depending on the ensuing reaction barriers, MgC2O4* during the forward discharge process may break down to MgCO3 and CO, or it may remain stabilized on the catalytic surface. CO is commonly formed on the catalytic substrate during the MgCO3 nucleation process. The generated CO could disproportionately result in C and CO2 or lead to the formation of MgCO3*, MgO*, and C*.