Poly(ethylene glycol)s [HO(CH2CH2O)nH, where n > 3] are highly active and selective in catalyzing dehydrochlorination of poly(vinyl chloride) in organic–aqueous hydroxide two-phase systems. Their catalytic activity and stability are much higher than those of widely used quaternary ammonium or phosphonium compounds. Poly(vinyl chloride) can be extensively dehydrochlorinated within half an hour at room temperature. The products are polyacetylene-like and have long polyene sequences according to their UV/visible, FT-Raman, and FT-infrared spectra. They can be doped by iodine to conductive states, with conductivities of 1–4 S cm−1. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2463–2469, 1998