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 3-11View all references, 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.