The electrolytic solvent characteristics of liquid nitrosyl chloride and general consideration of the factors affecting suitability of a system for isotope separation suggest that exchange reactions of NOC1 might provide an interesting and useful means for the separation of the stable isotopes of nitrogen or of chlorine, or of both in a simultaneous process. Vibrational frequencies of isotope substituted NOC1 molecules are calculated and used to estimate equilibrium constants for exchange of nitrosyl chloride with nitric oxide and with chlorine. Provisional experimental values of the equilibrium constants are given.