The electrochemical reduction of molten Li–Na–K carbonates at the eutectic composition was (43.5/31.5/25mol%) performed in the range 450–700°C. The analysis of the electrochemical mechanism was done by cyclic voltammetry with an inert vitreous carbon electrode. “Quasi-spherical” carbonaceous particles were obtained with average diameter comprised between 30 and 50nm. The specific surface area as well as the crystallinity and morphology of the powders were strongly influenced by the operating conditions, i.e. potential deposition, temperature of the molten carbonates, temperature of the drying process after washing. The carbon prepared in our experimental conditions contains micro-, meso- and macroporisty. The proportion of each one is strongly dependent on the operating deposition conditions. The highest specific surface area value (1315m2 g−1) was obtained with carbon powder deposited at 450°C for an applied potential of −6V and dried at 600°C under vacuum after washing.