1,2,4-Triazoline-3-thiones appear to be practically free from the tautomeric thiols. Oxidation with chlorine or bromine usually affords unstable sulphonyl halides which are readily converted into sulphonamides or, with some exceptions, into sulphonic acids. However, oxidative cleavage of the C–S bond with the formation of 3-unsubstituted or 3-halogenotriazoles occurs with some 2- or 4-substituted 1,2,4-triazoline-3-thiones, especially with bromine as the oxidising agent.