The experimental results obtained for the hydrolysis of p-nitrophenyldiphenyl phosphate (NPDPP) in the presence of sodium hydroxide (NaOH), micelles of cetyltrimethylammonium bromide (CTAB), and aqueous solutions of glycerol are described in terms of the pseudophase ion-exchange model (PPIE). The effect of glycerol on micelle formation and its influence on the reaction medium are also discussed. The results obtained indicate that the PPIE model is applicable for micellar catalysis in water-glycerol solutions.