The electrochemical reduction of carbon dioxide at a lead electrode Was Studied in alkaline aqueous medium. Chronoamperometry experiments combined with in situ reflectance spectroscopic measurements were performed after bubbling CO2 in an alkaline solution up to a pH value of 8.6. Combining information from E-pH diagram which provided the predominant species in the bulk solution and the adsorbed species determined spectroscopically, the results showed the only synthesis of formate from the electroreduction of hydrogenocarbonate. The identification of the different electroactive species allowed a reaction mechanism to be proposed for the transformation of hydrogenocarbonate into formate on the lead cathode. (C) 2009 Elsevier B.V. All rights reserved.