The reactions of γ-irradiated propionamide,n-butyramide, isobutyramide, methacrylamide, valeramide, and stearamide with sulfur dioxide have been studied by ESR spectroscopy, gas absorption measurements, and X-ray diffraction. Sulfur dioxide reacts with the radicals originally generated in the irradiated material to give sulphonyl radicals. These propagate in a chain reaction in which further sulfur dioxide is absorbed. In some cases the original radicals can be recovered from the corresponding sulphonyl radicals. The mechanism of the reactions is discussed.