The low-lying electronic states of the CaO2+ dication are investigated using high level ab initio calculations. The electronic states converging to the first and third dissociation limits are found to be thermochemically stable, with dissociation energies ranging from 0.17 eV to 0.83 eV. The electronic ground state is of 3Sigma− nature and the adiabatic double ionization energy of CaO is computed at 21.16 eV. The main spectroscopic constants of the five low-lying bound electronic states of CaO2+ are reported. The spin-orbit coupling terms related to the X3Sigma− and A3Pi states are computed and used to calculate the vibronic levels of these states.