To facilitate experimental studies on countercurrent reactors, a discrete contacting mode was worked out experimentally and theoretically. Enzymatic hydrolysis of penicillin G to phenylacetic acid and 6-aminopenicillanic acid was carried out in biphasic aqueous organic systems without pH control. The two phases were countercurrently contacted in a discrete manner, so that equilibrium was reached in each stage. Sets of three and five shake flasks served to mimic equilibrium stages in the countercurrent setup. It was shown that discrete countercurrent contact leads to the same extent of improvement of the equilibrium conversion as continuous countercurrent contact does, when compared to the batch situation. Therefore, discrete experiments may be used to simplify the development of continuous countercurrent reactors.