In this study, the electrochemical oxidation of acetaldehyde was investigated at activated massive DSA ® electrodes in acid medium, using differential electrochemical mass spectrometry (DEMS) and high-performance liquid chromatography (HPLC). The electrodes were prepared either by platinum electrodeposition or by depositing a highly nanodispersive-supported catalyst (Pt and Pt-Ni) over electrode surfaces with a Ti/Ru 0.3Ti 0.7O 2 nominal composition. Bulk electrolysis shows evidence of CO 2 and acetic acid formation. The electrocatalytic efficiency of the electrode material was also investigated as a function of the amount of catalyst added over the DSA ® electrode surface. The presence of RuO 2-active sites on the DSA ® substrate plays an important role in the reaction overall efficiency. The addition of platinum to DSA ® enhances the oxidation of acetaldehyde to CO 2. The role of the substrate on the direct activation of acetaldehyde oxidation is discussed on the basis of the direct application of the metal nanoparticle catalyst over conductive oxide surface based on Magneli phase (mixture of Ti n O 2 n−1 and other phases) from Ebonex ®.