CCSD(T) basis set limit bond dissociation energies by extrapolation for ClONO2 and CCSD(T)/cc-pV5Z estimates of bond dissociation energies for BrONO2 were calculated by determining correction factors to MP2/cc-pVXZ (X = 2-5) basis set energies. To obtain the MP2 basis set limit energies, MP2/ce-pVXZ (X = 2-5) level calculations were extrapolated to the basis set limit using either polynomial or exponential functional forms. Correlation effects were taken into account by calculating the difference in energies at the MP2/cc-pVTZ and CCSD(T)/cc-pVTZ levels. Subsequent corrections for the spin-orbit energy of the atomic fragment and zero point energy were applied to yield the final bond dissociation energies. The theoretical results are in good agreement with available experimental values and theoretical values calculated using isodesmic methods.