The extraction kinetics of Zn(II) from sulfate solutions with di-(2-ethylhexyl) phosphoric acid (D2EHPA) in isododecane was studied in a flat-sheet, membrane-based microcontactor. The potential of process intensification due to microstructured length scales, a dispersion-free contacting, laminar flow and the constant interfacial area allow a detailed view in reactive extraction kinetics, where the rate-determining step can be diffusion- or reaction-limited (or both in a mixed regime). The individual mass transfer coefficients can be manipulated by the experimental conditions, consequently, the chemical reaction resistance is negligible at high pH and high extractant concentrations and the extraction process is mainly governed by aqueous boundary layer resistance (>95%). Therefore, the developed diffusion model accounts for the overall mass transfer coefficient. In the next step, the reaction resistance is quantified at lower pH. The relative reaction resistance reaches up to 78% at pH 1.33. (C) 2015 Elsevier B.V. All rights reserved.