Sulphonylnitrosamides, ArS0,N (NO) R, when heated in inert solvents, undergo first order decomposition into nitrogen and alkyl arylsulphonates (ArS0,R). A mechanism involving an intermediate diazosulphonate (ArS0,ON = NR) is proposed. ... When a solution of p-tolylsulphonylmethylnitrosamide in toluene, nitrobenzene, anisole, decalin or chlorobenzene is heated above 95O, a considerable quantity of nitrogen (87-92 % ) is evolved. After removal of the solvent an oil remains, ...