A high-molecular-weight poly(2,5-dialkoxy-p-phenyleneethynylene) derivative has been prepared by the Heck reaction of 1,4-bis(2-ethylhexyloxy)-2,5-diiodobenzene and 1,4-diethynyl-2,5-dioctyloxybenzene. The highly luminescent polymer exhibits excellent solubility and can readily be processed into high-optical-quality films. The weight-average molecular weight (M) over bar(W) was 240000 g . mol(-1), with a polydispersity index of 2.9. Thermal analysis revealed a glass transition around 90 degrees C, and an onset of chemical-crosslinking at 130 degrees C. The high (M) over bar(W) and the remarkable solubility enabled the preparation of liquid crystalline solutions of the new PPE.