Soluble poly(m-phenylenevinylene) derivatives (4) were synthesized via Wittig-Horner reaction. The number-average degree of polymerization was estimated to be around 25-35. On the basis of FT-IR and H-1 NMR spectra, the olefins in the polymers were confirmed to be predominantly in the trans-configuration. A model compound, 3,5-distyryl-4-hexyloxytoluene (5), was also synthesized to aid the structural characterization. Comparison of photoabsorption and emission characteristics between 4 and 5 indicated that the m-phenylene effectively interrupted the conjugation, allowing predictable color control in the pi -conjugated polymers. At low temperature, the fluorescence of 4 was readily resolved into two peaks, suggesting the predominant emissions were from 0-1 and 0-2 transitions. Polymers 4 were found to be highly luminescent in both solution and film states. LED devices using 4 gave blue EL output (emission lambda (max) at 445 and 462 nm).