This research investigates the kinetics of the reaction between dissolved ozone and pentachlorophenol in acidic and neutral buffer solutions over the temperature range of 10° to 40°C. The reaction is very fast and five to six moles of ozone are required for conversion of each mole of pentachlorophenol. The overall kinetics are second order, with first order each in the concentrations of ozone and pentachlorophenol. At 25°C, the overall rate constant ranges from 7.55 x 104to 2.49 x 107L/Ms as the solution pH changes from 2 to 7. The ozonation rate increases as the fraction of pentachlorophenate in the solution increases, and the rate constant varies in proportion to [HO−]0.75in the pH range of about 2 to 5. The reaction is enhanced by temperature, and correlations by the Arrhenius equation yield an average activation energy of 27 kJ/mole.