Large-scale multi-reference configuration interaction MRD-CI calculations are performed to compute the electronic spectrum of C₆⁺ in its linear and cyclic conformation. The electronic spectrum of linear C₆⁺ is dominated by two transitions computed at 2.57 eV (²Π_g ← X ²Π_u) and at 5.80 eV (3 ²Π_g ← X ²Π_u). The first dipole-allowed transition of cyclic C₆⁺ is calculated at 0.58 eV (²B₂ ← X ²A₁) and this transition should help to identify cyclic C₆⁺ since there are no transitions of linear C₆⁺ in this energy region.