The kinetic modeling of intermediate products formed in the electrochemical treatment of phenolic wastewater with carbon electrodes was studied in a batch electrochemical reactor. The highly polluted synthetic wastewater was prepared at 3.243 mM initial phenol concentration, and the treatment was carried out at 25 degreesC with 120 g dm(-3) electrolyte concentration and 329 A m(-2) current density at 6 V cell voltage. In the reaction medium, mono-, di-, and trisubstituted chlorophenols formed successively and almost 100% of all species contributed to the formation of polymeric structure while being oxidized to some extent. A conversion/polymerization pathway mechanism was proposed, and the mathematical model was assessed with a numerical analysis technique of Himmelblau-Jones-Bischoff. The specific reaction rate constants were calculated using statistical functions of the Microsoft Excel 2000 solver program, and the differential rate equations were solved with Matlab 5.2. The simulated results represented the concentration profiles of phenol and chlorinated intermediates fairly well.