The [ ] and [ ] transitions of the CO2+ ion were photographed in emission under high spectral resolution. Analysis of the electronic band origin of the [ ] transition has provided rotational constants which are more refined and extensive than those previously known. The presence of a perturbation at J′ ~ 36.5 in the [ ] vibronic level was confirmed and a second stronger perturbation was shown to exist for values of J′ < 20.5.The four subbands 0110 2Πg–0100 μ2Σu, 0110 2Πg–0120 2Δu5/2, 0110 2Πg–0120 2Δu3/2, and 0110 2Πg–0100 κ2Σu of the Renner–Teller split [ ] vibronic transition 010–010 were identified and rotationally analyzed. The results lead to values of [ ], [ ], [ ], and [ ].