An attempt to isolate excited nitrogen molecules from the reaction of active nitrogen with iodine proved unsuccessful. The rate constant of the bimolecular reaction between nitrogen atoms and iodine cyanide was found to be 3.5 x 10-¹⁴ cm³. molecules-¹ sec-¹. with a probably as small temperature coefficient. A mechanism has been proposed for the excitation of the CN emission from the reaction of active nitrogen with the cyanogen halides.