AbstractThe electrochemical behavior of thiocinnamamide in aqueous solutions with 5% (v/v) ethanol was studied by dc and ac polarography and cyclic voltammetry. In acidic media, the reduction of thiocinna mamide occurs in the adsorbed state, giving a single dc wave. In alkaline solutions, the reduction starts at the negative limit of the adsorption potential range and produces two poorly separated dc waves. The first corresponds to the reduction of the adsorbed molecules with a strong dependence of the adsorption coefficient on the electrode potential. The second is due to the irreversible reduction of nonadsorbed molecules. This reaction involves a slow chemical step. The reduction results in the fission of the carbon‐sulfur bond. Another reaction is the hydrolysis of adsorbed molecules (in the absence of any charge‐transfer step), giving the nitrile of cinnamic acid. This compound is also formed in the range of the anodic wave of thiocinnamam