The structure and vibrational frequencies are reported for the OCCN radical and its cation using quadratic configuration interaction and complete active space self-consistent field methods. The heat of formation for the OCCN radical is estimated as 50,2 kcal mol(-1). The adiabatic ionization potential is estimated as 8.5 eV. Vertical excitation energies for low-lying excited states of OCCN are also reported. (C) 1997 American Institute of Physics.