Measurement of single-electron capture (SEC) and translational energy spectroscopy (TES) of the triatomic dications CO2+2, OCS2+, CS2+2 at high product ion resolution (typically 0.6 eV) is facilitated by a novel translational spectrometer. Calibration of SEC spectra allows the detection and precise assignment of observed state-selective processes; TES data indicate the presence of dication state having the same spin symmetry. Since single and double ionisation of each triatomic neutral ACB (where A and B represent O and S) to low-lying cation states occurs by removal of essentially non-bonding electrons, the bond lengths and energies of each ACB, ACB+ and ACB2+ are similar. Therefore, current data permit the evaluation of electronic levels of the triatomic dications in excellent agreement with previous experimental and theoretical work. A systematic procedure for future investigations of multiply charged molecular ions is proposed.