The behavior of potassium hydrogenperoxomonosulfate (KHSO5) has been studied using alternating current voltammetry with square wave modulation in potential range +1.0…–1.2 V at carbositall electrode as indicating and auxiliary electrode (reference electrode Ag, AgCl/KСl(sat)) (Ep = +0.25 V). A linear relationship between peak current and concentration was obtained in the range 0.9´10–5 mol L–1 to 5.4´10–5 mol L–1 of the KHSO5 concentrations at pH ~ 0.8 for pure substance. It is Ip = (8.3 ± 0.6)´103´Ãƒâ€˜Ã‚ (r = 0.999). RSD were 2.68 %, 2.55 % and 2.39 % for the 3.6´10–5, 4.5´10–5 and 5.4´10–5 mol L–1concentrations of KHSO5 model solutions, respectively (δ = –0.28…+0.44 %). The addition method was used for KHSO5 determination in disinfectant "Ecocid S", RSD were 2.01 % and 1.88 % for с(KHSO5) = 4.65´10–5 and 7.75´10–5 mol L–1, respectively. The obtained results have good agreement with those obtained by using the reference method of iodometric titration, with an accuracy lower than – 0.42 %.