The oxidation of simple aliphatic sulphides [MeSMe, EtSEt, (CH₂)₄S] by hydroxyl radicals occurs via a complex reaction mechanism. The first step is addition of the OH· to sulphur to form R₂ṠOH radicals. At low sulphide concentrations (< 10^–4M) R₂ṠOH rapidly eliminates H₂O to form a RSR(–H)· radical which may be described by the mesomeric forms –CH–[graphic omitted]– and –CHṠ–. This radical is ultimately also formed at higher sulphide concentrations but via a different pathway. R₂ṠOH increasingly reacts with another R₂S molecule to form a short lived (R₂S)₂OH· radical complex which dissociates to (R₂S)₂⁺ and OH^–. The (R₂S)₂⁺ complex ion seems to be relatively stable and decays essentially via equilibration to the molecular cation R₂S⁺. This ion in its reaction with the solvent, OH^– ions, and through a bimolecular process with another R₂S⁺ cation is effectively deprotonated to form the RSR(–H)· radical. The reaction route at high concentration includes the formation of transient species with oxidizing properties; Fe(CN)₆^4– is rapidly oxidized by (R₂S)₂⁺[and possibly (R₂S)₂OH·]. The RSR(–H)· radical partially disproportionates to negative and long lived (>1 ms) positive ions. The stable oxidation product, sulphoxide, has been identified.