The simple stirring of phenol with an oxidant in water provided a novel green way to synthesize soluble polyphenol. The soluble polyphenol obtained had a high poly(phenylene oxide) unit ratio, poly(phenyleneoxide)/ poly(phenylene) 0ca. 80/20. Additionally, the insoluble fraction was identified as a poly(phenyleneoxide), which has a crosslinking point for every 5.5 )10 3 molecular weight. These results suggest that oxidative polymerization in water can be run in a manner to control the coupling selectivity of phenol. Both the soluble polyphenol and the insoluble fraction showed a high thermal stability. Oxidative polymerization in water provides the potential for a formaldehyde-free and regioselected soluble poly(phenyleneoxide) from phenol.