A new set of dithienyl polyphenylenes was prepared with a view of developing sulfur-containing polyaromatic hydrocarbons (PAHs) by oxidative cyclodehydrogenation. The first of these, 1,2-bis(5-methyl-2-thienyl)-3,4,5,6-tetra-(4-tert-butylphenyl)benzene (1) was sterically hindered at the 5-positions of the thienyl rings and under Lewis acid catalyzed cyclodehydrogenation gave monomeric intramolecularly fused dithienyl 3, which was spectroscopically and structurally characterized. Under the same conditions, three unhindered dithienyl polyphenylenes, 1,2-(thienyl)-3,4,5,6-tetra(4-tert-butylphenyl)s 2, 5, and 6, underwent both thiophene-di-