Asymmetrically disubstituted poly(2-methoxy-5-methyl-1,4-phenylenevinylene) (PMMPV) and a series of poly(1,4-phenylenevinylene-co-2-methoxy-5-methyl-1,4-phenylenevinylene)s (poly(PV-co-MMPV)) were synthesized through a water-soluble precursor route. These polymers were characterized using UV-visible, FT-IR spectroscopy, and a DSC, TGA thermal analyzer. The electrical conductivities of the polymers were investigated by the four-in-line method at room temperature. A PMMPV film can be stretched up to 5 times and doped with FeCl3 and I-2 to give electrical conductivities of 27 and 7.4 S/cm, respectively, along the drawn direction. In copolymers, as the content of the MMPV unit increases, the electrical conductivity steadily increases. The chi((3)) (-3 omega; omega, omega, omega) value of PMMPV was determined by the third harmonic generation (THG) technique at 1907 nm, the fundamental wavelength. The measured chi((3)) value was 7.5 x 10(-12) esu.