The anodic process on glassy carbon electrodes in molten CaCl2 containing CaO was investigated at 1123 K by cyclic voltammetry and convolution voltammetry. It was found that the oxidation sequence occurs through a consecutive two-step electrochemical reaction: O2-(diss) + xC --> CxO(ads) + 2e and O2-(diss) + CxO(ads) --> CO2(gas) + (x - 1)C + 2e. Both steps were found to be irreversible. Experimental data indicate that the first electrochemical step is preceded by the dissociation of a complex. The diffusion coefficient of the oxygen-containing species, the charge-transfer coefficient, and the charge-transfer rate constant were found equal to 2.0 x 10(-6) cm(2) s(-1), 0.43, and 1.8 x 10(-5) cm s(-1), respectively.