A simplified population balance model is presented to describe the hydrodynamics of the dispersed phase within a Kuhni column. This model is fitted to experimental axial drop size distribution profiles by the optimization of expressions for the breakage and coalescence rate coefficients. Thus, over the experimental range of study correlations for these rate coefficients are developed respectively as breakage, Br-ij = 3.0N(u(ij)/H-s) exp[(-1.8 x 10(-4)DF(phi))/(N(2)d(i)(5/3))], and coalescence (h lambda)(ij) = 0.640(u(ij)/H-s)phi(j)(-1.3)v(i)(0.56). These expressions indicate that the breakage and coalescence rate coefficients are much less dependent upon rotor speed than suggested by correlations in the literature for turbulent stirred tanks. In contrast, as suggested by Gourdon et al. (Chem. Eng. J. 1991, 46, 137), these coefficients are correlated with the drop residence time, which in turn is determined by the individual droplet velocities.