The electrochemical oxidation of thiourea on a Pt electrode was studied at different potentials by use of voltammetry and in situ FTIR spectroscopy. It was found that during the first step the thiourea could be oxidized to the c,c’-dithiodiformamidinium ion in 1 M NaCl solution. It could be further oxidized at higher potentials to produce cyanamide, HSO4- and SO42- ions through an electrocatalytic oxidation process of chemisorbed sulphur taken on the surface of the platinum electrode.