A [Rh(cod)Cl](2) and cationic bipyridyl ligand system was found to be an efficient catalyst for the polymerization of phenylacetylenes in water under aerobic conditions at room temperature. Poly(phenylacetylene) was obtained in high yield with high molecular weight and cis content, and the reused aqueous phase showed activity for recycle run. Mono-substituted phenylacetylenes could also be polymerized by this system in the presence of KOH.