An ab initio study on three hypothetical nitrogen-oxygen clusters is presented. The investigated systems are N2O3, N4O6, and N8O12 with highly symmetric geometries, D-3h, T-d, and O-h symmetry, respectively. Calculations were performed at SCF and MP2 level (MP2, for the two smallest clusters only). Several basis sets were used, from 3s2p to 4s3p2d1f, depending on the cluster size. These structures were found to have local minima, with energies very high above the products of a fragmentation reaction (N-2 and O-2). According to these calculations, NO clusters are potentially interesting as high-energy-density materials.