The cyanogen di-N-oxide molecule (ONCCNO) has been generated in high yield from in situ flow pyrolysis reactions of gaseous dichloroglyoxime or dibromofuroxan precursors and studied for the first time in the gas phase. This structurally novel transient species is characterized by HeI photoelectron, HeI/HL(alpha) photoionization mass, and mid-infrared spectroscopies. To complement the experimental aspects, an assessment of the structure and bonding of ONCCNO is obtained from ab initio calculations at the HF, MP2, MP,3 and MP4SDQ/6-31G* levels of theory. Both the calculations and the spectroscopic results suggest that the molecule has a linear or quasi-linear structure.