The electrocatalytic oxidation of glyoxylic acid in acid medium on platinum electrodes has been investigated. The oxidation mechanism proposed excludes any dissociative adsorption of the organic molecules. This fact is explained as the consequence of the stabilization of the C-H bond in the aldehyde group induced by the deactivating and polarizing effects exerted by the carboxylic group. Ideas for the explanation of oxidation currents produced by aldehydes, alcohols, and other organic compounds in the potential range corresponding to the double-layer charging are given in the context of the discussion of the glyoxylic acid electro-oxidation mechanism.