Abstract Aqueous phenol solutions were treated with hypochlorite at 20°C under various experimental conditions. Changes in the composition of the chlorination products in water were determined by using gas chromatographic (GC) and GC-mass spectrometric analyses of diethyl ether extracts. Chlorination of phenol in dilute aqueous solution produced a series of highly chlorinated compounds, including chlorophenols, chlorobenzoquinones and chlorinated carboxylic acids. Tentative identifications were also made for other compounds with the following proposed molecular formulae: C 12H 8Cl 2O 2, C 12H 7Cl 3O 2, C 12H 6Cl 4O 2 and C 12H 5Cl 5O 2. On the basis of thin-layer chromatographic and GC behaviour, these compounds are considered to be chlorinated phenoxyphenols. Production of some of these compounds is dependent on the equivalents of chlorine per mole of compound and the reaction pH. These results show that treatment with chlorine of water contaminated with phenolic compounds leads to the production of chlorinated phenoxyphenols.