The energies of some doubly-charged molecular ions are calculated using the new semi-empirical MO method HAM/3. The calculated energies are compared with the corresponding mass spectrometric appearance potentials and energies from Auger spectra. Both small molecules (N2, CO, H2O2, NH3, CO2, N2O and C3O2) and large molecules (benzene, toluene and naphthalene) have been considered. © 1979.