The kinetics of extraction of copper(II) from aqueous solutions containing an equimolar amount of EDTA (ethylenediaminetetraacetic acid) with Aliquat 336 (a quaternary amine) in kerosene were studied using a microporous membrane-based stirred cell. This device could give the intrinsic reaction rate for the formation of the amine complex occurring at or near the organic-aqueous interface by eliminating the diffusion resistances. Experiments were performed as a function of aqueous pH (3-11), copper(II) concentration (0.79-3.14 mol.m(-3)), Aliquat 336 concentration (50-500 mol.m(-3)), and temperature (288-318 K). The experimental results showed that Aliquat 336 would adsorb at the interface and react with the Cu-EDTA chelated anions.