(Figure presented.) 2-Thietane-containing 5-bromo-2,4-dihydro-1,2,4-triazol-3-ones were synthesized from 3,5-dibromo-1-(thietan-3-yl)-1,2,4-triazole by the reaction with sodium hydroxide solution followed by oxidation of the resulting 5-bromo-2-(thietan-3-yl)-1,2,4-triazol-3-one to 5-bromo-2-(1-oxothietan-3-yl)-2,4-dihydro-1,2,4-triazol-3-one and 5-bromo-2-(1,1-dioxothietan-3-yl)-2,4-dihydro-1,2,4-triazol-3-one. For the synthesis of isomeric 4-thiethane-containing 5-bromo-2,4-dihydro-1,2,4-triazol-3-ones, the protective dioxothietanyl group of 5-bromo-2-(1,1-dioxothietan-3-yl)-4-(thietan-3-yl)-1,2,4-triazol-3-one was removed by a treatment with sodium ethoxide followed by oxidation. The reactions of 2/4-thiethane-containing 5-bromo-2,4-dihydro-1,2,4-triazol-3-ones with 2-(chloromethyl)thiirane leading to the formation of regioisomeric 5-bromo-2,4-di(thietan-3-yl)-2,4-dihydro-1,2,4-triazol-3-ones were studied. 5-Bromo-2,4-di(1-oxothietan-3-yl)-2,4-dihydro-1,2,4-triazol-3-ones, 5-bromo-2,4-di(1,1-dioxothietan-3-yl)-2,4-dihydro-1,2,4-triazol-3-ones, and 5-bromo-2/4-(1-oxothietan-3-yl)-2/4-(1,1-dioxothietan-3-yl)-2,4-dihydro-1,2,4-triazol-3-ones were synthesized by oxidation reactions. A number of the synthesized compounds showed antidepressant activity. © The Author(s) 2024.