The reactions of phenol with dichloromethane using quaternary ammonium salts as a liquid-liquid phase-transfer catalyst in an organic solvent/ alkaline solution were investigated. The technique of phase-transfer catalysis had a dramatic accelerating effect on the reaction and increased the yield of diphenoxymethane by more than 95%. The effects of catalysts, temperature, and basic concentration on reaction rate were studied in order to find the optimum operating conditions for this reaction. Experimental results indicated that a potassium hydroxide was preferred over sodium hydroxide in order to enhance the reactivity of the reaction. The reaction rate constant and the distribution coefficient of the intermediate product were obtained. During the reaction, the concentration of the intermediate product was also measured in order to study its behavior in the liquid-liquid system.