The kinetics of the hydrolysis of trichloromethylbenzene in water-acetone solutions have been studied over the temperature range 30-45 degree C. The rate of the reaction have been followed by conductance measurements. The rate is first order with respect to the trichloromethylbenzene and is independent of the concentration of water. When the concentration of water in the solvent is increased, the hydrolysis rate constant first decreases to a minimum at about 0. 5 water mol fraction, then increases. The influence of solvent variation on reaction rates has been examined in terms of changes in activation parameters. The results are discussed in terms of the electrostatic theory, polarity of the medium and on the change in the solvent structure.