Homocysteine thiolactone (I) was acylated with XCOCHR(CH2)nX (R = H, X = Cl, n = 0, 1; R = Me, Et, X = Br, n = 0) to give haloacyl derivatives II, which were converted into thioglycolic acid derivatives III (R = H, R1 = H, Ph, C6H4NO2-p, C6H4OMe-o, n = 0; R = Me, R1 = K, Et, n = 0; R = R1 = Et, n = 0; R = H, R1 = Et, n = 1).Thus, II (R = H, X = Cl, n = 0) was treated with HSCH2CO2H to give III (R = R1 = H, n = 0) (IV).The structure of IV was determined by 1H and 13C NMR spectroscopy.III exhibited mucolytic activity in rabbits with acute bronchitis.