Oxidation of (E)-3-aryl-2-cyanothioacrylamides under the action of the Et2S(O)-HCl system leads to the formation of (2E,2 ' E)-2,2 '-(1,2,4-thiadiazole-3,5-diyl)bis[3-arylacrylonitriles] in 54-91% yields. Structure of the obtained compounds was confirmed by the two-dimensional NMR spectroscopy data. A plausible reaction mechanism was discussed. Two compounds showed a pronounced antidote effect against 2,4-D herbicide in a laboratory experiment on sunflower seedlings in the absence of growth-stimulating activity.