The products formed when methyl mercaptan reacts with polysul-fide in an alkaline solution have been identified, using1H NMR, as dimethyldisulfide, dinethyltrisulfide, dimethyltetrasulfide and methyldisulfide anion (CH3SS−). Analogously, methyl mercaptan and polythionate were found to give methylthiosulfate anion (CH3SSO3−), in addition to these dimethylpolysulfides. The reactions are interpreted in terms of nucleophilic displacements of the SN2 type. The formation of these anionic products constitutes the basis for the potential use of polythio compounds for reduction of air pollution in the kraft pulping process.