The mechanism of the electrochemical oxidation of thiocyanate anion in acetonitrile was studied by cyclic voltammetry, chronoamperometry, electrolysis, digital simulations and quantum chemical calculations. The experimental data indicated complex character of the reaction mechanism, which includes reactions of thiocyanate anion with the products of its oxidation, thiocyanate radical and thiocyanogen. It was proposed that the last reaction takes place in the reduction of thiocyanogen as well. The DFT PCM-SMD M06–2X/aug-CC-pVQZ calculations show that the reaction of thiocyanate anion with thiocyanate radical and disproportionation of thiocyanogen anion radical are thermodynamically favorable. The effects of the mentioned reactions on the shape of the curves of cyclic voltammetry and chronoamperometry as well as that of the mass transfer regime are discussed.