Dimeric TTFs have been synthesized by using palladium-catalyzed reactions. Although TTFs are very sensitive under oxidation conditions, the palladium-catalyzed reactions can be successfully employed for the oxidative coupling of TTF derivatives. The chemical oxidation of dimeric TTFs produced cation-radicals, dications, and tetracations selectively. Electronic spectra of the cation-radicals clearly indicate the magnitude of the intramolecular interaction between two TTF moieties.