In the title compound, C17H10S5, the dithiine ring adopts a boat conformation while the dithiole ring has an envelope conformation. The phenyl groups are planar and make dihedral angles of 40.7 (2) and 59.8 (2)degrees with the best plane of the thiine ring. The shortest intermolecular S . . .S contact is 3.305 (2) Angstrom.