Sulphides have been oxidised with an anhydrous solution of hydrogen peroxide in tertiary butyl alcohol containing a catalytic amount of vanadium pentoxide to give sulphones and sulphoxides. This method was very useful for the partial oxidation of labiles sulphides (e.g.α-chloro-sulphides, and α-acetoxy-sulphide, and thiiran) to sulphoxides of high purity. A reported preparation of 2-hydroxymethylthiiran and the corresponding sulphone has been shown to yield instead 3-hydroxytheitan and 3-hydroxythietan 1,1-dioxide.