The electrocatalytic oxidation of lactose was performed in carbonate buffered solutions. The electrolysed solutions, analysed at regular periods of time by chromatography, showed that lactobionic acid was the only important reaction product when the oxidation was carried out on lead-adatom-modified platinum electrodes. Confirmation was obtained by means of additional spectroscopic techniques like H-1 nuclear magnetic resonance and gas chromatography-mass spectroscopy. A mechanism for the first steps of the reaction is tentatively suggested.