The oxidation of the 1, 2, 3, 4-thiatriazol-5-thiolate ion CS2N−3by, permanganate ions in an alkaline medium was investigated. The pseudo-halide undergoes a quantitative seventeen-electron change reaction yielding sulphate, nitrogen and carbon dioxide as final products. Despite the similar chemical behavior exhibited by thiocyanate and CS2N−3ions the experimental data strongly suggested that the oxidation reactions of the pseudo-halides dealt with in this study do not follow the same mechanism. On the basis of this reaction an oxidative analytical method was developed for the CS2N−3. The pseudo-halide is oxidized by an excess of permanganate ions. The remaining oxidant is titrated with standardized thalium (I) or hexacyanoferrate (II) solutions. Considerable improvements over former procedures were achieved employing two polarized platinum electrodes to detect the end point, by potentiometry. The method proposed here is simple, precise, accurate, rapid and allows the determination of pseudo-halide concentrations down to 1 × 10−3M.