The crystal structure of the title compound, [Cu(C12H8N2)2I]I, S8, has been determined by X-ray diffraction at 295(1) K and refined by least squares to R 0.066 (2031 ‘observed’ reflections). Crystal data: orthorhombic, Pbcb, a 7.984(5), b 16.690(4), c 22.986(12) Å, Z 4. The structure comprises five-coordinate trigonal bipyramidal [Cu(phen)2I]+ cations (I equatorial) lying on the 2 axes parallel to a which pass through the Cu-I bonds, together with iodide anions, and lattice S8 molecules, also lying on 2 axes but parallel to b. In the cation, Cu-I is 2.672(3), Cu-N (equatorial) 2.10(1) and Cu-N (axial) 2.00(1) Å. S-S ranges from 2.004(7) to 2.059(7). There appears to be no significant interaction between the octasulphur molecules and any other species.