Ab initio electronic structure calculations are employed to investigate the cage isomer of N2O3 (c-N2O3) as a viable energetic oxidizer. c-N2O3 is vibrationally stable with a large heat of formation of 7.95 kJg(-1) and can produce larger enthalpies of combustion than other commonly used oxidizers such as ammonium perchlorate, O2(l) and N2O4. c-N2O3 is shown to have a unimolecular decomposi-tion barrier of 24.4 kJmol(-1) at the CCSD(T)/CBS(Q-5) level of theory, and a dimer-induced decomposition barrier of 100.8 kJmol(-1). Although c-N2O3 is predicted to perform well as an oxidizer, the low barrier to unimolecular decomposition is likely to render it impractical as an energetic oxidizer.