Investigations of mass transfer behavior with the standard test system of the European Federation of Chemical Engineering (EFCE) for the reactive extraction zinc + D2EHPA (di(2-ethylhexyl) phosphoric acid) were carried out. Experiments were performed with single droplets in a mass transfer cell on lab-scale. In the experiments, contact time for the mass transfer between droplets and continuous phase, concentrations of zinc, D2EHPA and sulfuric acid, diameter of droplets and hole-diameter of sieve trays were varied. These experimental results show a systematic investigation of single droplet mass transfer behavior for the standard test system of the EFCE for the reactive extraction of zinc with D2EHPA. In the mass transfer model reported here, all transient effects are considered with an instability parameter, which was determined through experiments in a mass transfer cell. The simulation results with obtained instability parameters are in a good agreement with the experimental results. (c) 2011 American Institute of Chemical Engineers AIChE J, 2012