[en] The influence of the internal energy content, either vibrational or electronic, on the probability of CO elementary processes induced by electron-impact is investigated. In particular the vibronic excitations of the first singlet state of the CO spectrum, A ¹Π, are derived in the framework of the similarity approach, characterizing also the radiative properties to the ground electronic state. Moreover the ionization of the ground state to the first three states of the molecular ion are calculated with the binary-encounter-dipole model, investigating the branching ratio of the three channels and their vibrational dependence. Finally the total ionization of the CO metastable a ³Π state is considered in the binary-encounter-Bethe approach. (paper)