The electrochemical reduction of carbon dioxide on a lead electrode was studied in aqueous medium. Preliminary investigations carried out by cyclic voltammetry were used to determine the optimized conditions of electrolysis. They revealed that the CO 2 reduction process was enhanced at a pH value of 8.6 for the cathodic solution i.e. when the predominant form of CO 2 was hydrogenocarbonate ion. Long-term electrolysis was carried out using both potentiometry and amperometry methods in a filterpress cell in which the two compartments were separated by a cation-exchange membrane (Nafion Ò 423). Formate was detected and quantified by chromatography as the exclusive organic compound produced with a high Faradaic yield (from 65% to 90%). This study also revealed that the operating temperature played a key role in the hydrogenation reaction of carbon dioxide into formate in aqueous medium.

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