A film of niobium oxide was immobilized on a SiO 2/C carbon–ceramic matrix (specific surface area 270 m 2 g −1) and characterized by N 2 adsorption–desorption isotherms, scanning electron microscopy, X-ray photoelectron spectroscopy and atomic force microscopy. This new carbon–ceramic material, SiO 2/C/Nb 2O 5, was used for construction of electrodes, and it shows ability to improve the electron-transfer between the electrode surface and ascorbic acid. The electrocatalytic oxidation of ascorbic acid was made by differential pulse and cyclic voltammetry techniques, making it potentially useful for developing a new ascorbic acid sensor.