Recent studies have suggested that octanitrocubane and heptanitrocubane may be two of the most powerful non-nuclear high-energy materials currently known. Progressive substitution of the hydrogen atoms on cubane for nitroso groups is expected to also produce a new potential high-energy material, which should have thermodynamic properties similar to nitrocubane. In this study we predict optimized structures, vibrational frequencies, enthalpies of formation, and specific enthalpies of combustion for a series of nitrosocubanes ranging from mononitrosocubane to octanitrosocubane. Our results indicate, on the basis of the specific enthalpies of combustion alone, that mononitrosocubane should make the best new high-energy material; however, we speculate that the velocity of detonation of octa- and heptanitrosocubane will make them better high-energy materials.