Poly(2,5-di-n-butoxyphenylene) (4) was prepared by oxovanadium-catalyzed oxidative coupling polymerization of 1,4-di-n-butoxybenzene (3). Polymerizations were conducted in 1,2-dichloroethane in the presence of VO(acac)(2), CF3SO3H, and (CF3CO)(2)O under an oxygen atmosphere at roam temperature and produced polymer 4 having number-average molecular weight up to 12 000. VO(acac)(2) acted as an oxidative catalyst and the polymerization proceeded in the presence of 7.5% VO(acac)(2) (based on the monomer). The structure of polymer was characterized by H-1- and C-13-NMR spectroscopies and was estimated to consist almost completely of 1,4-linkage. The polymer was readily soluble in common organic solvents and could be processed into uniform films from solution. Thermogravimetric analysis showed 10% weight loss at 385 degrees C in nitrogen.