The droplet breakage in a coalescence-dispersion pulsed-sieve-plate extraction column (CDPSEC) was studied with 30%TBP (in kerosene)-water as a working system, and the organic phase as the dispersed phase. Because of the periodically arranged plates of every one coalescence plate with three dispersion plates in the CDPSEC, the droplets could coalesce and break up periodically. The drop size and its distribution were not kept at the constant values along the height of the column. It was found that the initial drop size distribution generated by the coalescence plate could be described with a normal distribution function. A mathematical model based on the population balance theory was developed to describe the drop size distribution along the column if only the drop breakage 'Was considered when drops passed through the dispersion plates. The mean drop size and its distribution calculated by the model were in good agreement with the experimental results. (C) 2004 Elsevier B.V. All rights reserved.