Carbon paste electrodes modified either by mixing palladium powder to the electrode material or by electrodepositing Pd via cycling the potential between 0.4 and -0.7 V (versus SCE) exhibited stable electrocatalytic response for aliphatic aldehydes and aliphatic alcohols. The aldehydes ( e g , formaldehyde) could be reduced to the corresponding alcohols (e.g., methanol), and the alcohols ( e g , methanol) could be oxidized to the corresponding aldehydes (e.g., formaldehyde) by direct current voltammetry (DCV). The electrocatalytic effect was attributed to the electrogenerated metallic palladium at the electrode surface. The cathodic current peak, the height of which was proportional to the aldehyde concentration, had negative values; it was ascribed to a desorption of the product of the electrode reaction from the surface of the electrode. This peak was used for quantitative analytical purposes.