The solubilizing ability of four nonionic surface-active agents is quantitatively compared. The critical micelle concentration (CMC) of the surface-active agents was evaluated from the solubility curves. The effect of the surface-active agents on the rate of hydrolysis of benzocaine and homatropine was investigated. At a concentration of surface-active agent less than the CMC, the surface-active agents do not significantly affect the rate of hydrolysis of the esters. At a concentration exceeding the CMC, the surface-active agents enhance the stability, due to micellar interaction.