The reactions of CH3CH2NH and (CH3CH2)(2)N radicals with NO have been studied using quantum chemistry methods. The results show that formation of the nitrosamines CH3CH2NHNO and (CH3CH2)(2)NNO is similar and that both isolated molecules are thermally stable. The nitrosamine formation reaction is highly exothermic, and the hot CH3CH2NHNO may undergo isomerization and subsequent reaction with O-2 to form the corresponding imine, CH3CH=NH. Time-dependent density functional theory (TDDFT) calculations show little difference of the vertical excitation energy between the pi* <- n transitions in CH3CH2NHNO and (CH3CH2)(2)NNO, and both will readily photolyze under sunlight conditions.