Three α-coupled terthiophenes, substituted on the terminal positions with methyl, thiomethyl, or bromo substituents, were photooxidized in a solvent mixture of methylene chloride and trifluoroacetic acid to form cation radicals. Visible, near-IR, and ESR spectra are reported. It is shown that the photooxidation requires oxygen and is acid catalyzed. In acetonitrile/trifluoroacetic acid, cation radical π-dimers are formed. Using Nafion, stable films of the cation radical dimer or dication of 2, 5ʺ-bis(thiomethyl)terthiophene could be formed.