Regiocontrolled poly(3-(4-dodecylphenyl)thiophene) was prepared by oxidative coupling polymerization of 3-(4-dodecylphenyl)thiophene using an oxovanadium complex as an oxidation catalyst. Polymerizations were conducted in the presence of vanadium acetylacetonate, trifluoromethanesulfonic acid and trifluoroacetic anhydride under oxygen atmosphere in 1,2-dichloroethane at room temperature. The structure of the resulting polymer was characterized by means of H-1- and C-13-NMR spectroscopies, and consisted of head-to-tail linkage. Degenerate four-wave mixing (DFWM) measurements of this polymer yielded the third-order susceptibility as high as 5.1 x 10(-10) esu.