Abstract: Breakage and coalescence rates of droplets in reciprocating plate extraction columns were investigated bystep change in mixing intensity.Mean drop size was measured by laser light transmission technique combinedwith measurement of local holdup.Batch and countercurrent flow experiments with and without mass transferoccurring show that the dispersion mechanisms are different.The Monte Carlo simulation by digital computerwas used to treat the experimental data and models of breakage and coalescence rates were obtained.