A novel, water-soluble Rh complex, (nbd)Rh[PPh2(m-NaOSO2C6H4)] [C(Ph)=CPh2] (1) was synthesized by the reaction of [(nbd)RhCl](2), Ph2P(m-NaOSO2C6H4) and Ph2C=C(Ph)Li, whose structure was determined by NMR and IR spectroscopies. The Rh catalyst 1 induced the polymerization of phenylacetylene (PA) in water to give two kinds of polymers; one was soluble in organic solvents such as tetrahydrofuran (THF) and CHCl3, and the other was insoluble in common organic solvents. The polymerization of sodium p-ethynylbenzoate (p-NaOCO-PA) homogeneously proceeded with 1 in water at 60 degreesC to give the polymer in high yield. Poly(p-NaOCO-PA) was treated with 1 N HCl and then reacted with (CH3)(3)SiCHN2 to obtain poly(p-MeOCO-PA). The methyl-esterified polymer was insoluble in THF and CHCl3, which suggests that the formed poly(p-MeOCO-PA) has cis-cisoidal structure. The polymer obtained from the polymerization of [p-CH3(OCH2CH2)(2)O2CC6H4]C=CH with 1 in water was soluble in methanol, ethanol, and THF, and partly soluble in water. (C) 2004 Wiley Periodicals, Inc.