The radical cation (3˙+), the radical anion (3˙–) and the, diamon (32–) of 2,3,9,10,16,17,23,24-octaethyltetraoxa[26]porphyrin were generated from the neutral compound (3) and the dication (32+). The electronic spectra of these five redox stages resemble those in the tetraoxaporphyrin series, 12+, 1˙+, 1,1˙– and 12–, but are shifted to lower energies by 0.7–1.0 eV. Thus, the Soret and Q bands of the four charged species, 32 +, 3˙+, 3˙– and 32–, lie at 450–600 and 700–1300 nm, respectively. The spectrum of the neutral 3 is characteristic of 4nπ-systems. The absorption bands were assigned to electronic transitions with the use of PPP calculations. The diions 32 + and 32– are predicted to preserve the symmetry D4h of the π-system with cyclic delocalization along the 28-membered perimeter, whereas in the neutral 3 the symmetry is lowered to D2h with localization of the double bonds. The four oxygen atoms in 32+ should bear one positive charge which is only slightly decreased on consecutive reductions, so that the additional negative charges are taken up almost exclusively by the perimeter. Proton-coupling constants were determined for the radical cation 3˙+ and the radical anion 3˙– by EPR spectroscopy. Within the limits of experimental resolution, they are the same for both radical ions and consistent with an effective D4h symmetry. The large inherent width of the EPR lines–and their reluctance to saturation–point to a degenerate or nearly degenerate ground state of 3˙+ and 3˙– undergoing a dynamic Jahn–Teller effect.