The photolysis of CF3CN at 1849 Å has been studied. The major products are hexafluoroethane, cyanogen, and perfluoro-3-methyl-2-aza-2-butene. The experimental value for [Formula: see text]is:[Formula: see text]where:[Formula: see text]Another product was isolated in smaller amounts and has been tentatively identified as perfluorotrimethyl-aza-2-pentene.