The electrocatalytic oxidation of lactose has been studied on nanolength scale Au-colloids (5 nm) embedded in carbon felt as electrode (Au-NMC). A preliminary investigation by cyclic voltammetry, used to determine the optimized conditions of electrolysis, showed that the current densities were higher than those obtained on a gauze electrode of gold (Au-GE) with a surface area three times greater. Long-time electrolyses were carried out using a two potential plateau program with different values for the oxidation potentials. Chromatographic and NMR analyses showed that the oxidation of lactose led mainly to lactobionate (91%).