Experimental studies were performed on the perforated-plate extraction column with reciprocated flow, utilizing the characteristics at lower operating limit of the pulsed plate column.By employing the method of pulsation as shown in Fig. 1, the efficiency of extraction was raised to the higher level because the liquid-mixing occurring across the plates was obstructed, and the capacity coefficient was expressed by a simple formula due to the simplicity of the operating conditions.The capacity coefficient increased with the decrease in diameter of the perforations, but the distance between the centers of the perforations had to be larger than the frontal diameter of the ellipsoidal drops. If not, the capacity coefficient would become lower, since the rising drops would combine with each other and the effective surface for the extraction would decrease.The holdup of the dispersed phase was observed to consist of two parts:-static holdup and operating holdup. The static holdup was of such a quantity as would be indispensable for the ispersed phase to drench the surface of the plate and spout uniformly through the plate, and the operating holdup was decided by the relation between the periodic time of the pulsation and the time needed for the dispersed drop to spout through the plate and combine with the upper organic solvent layer.