Many chemical engineering processes occur under conditions when a dispersed phase undergoes fragmentation (breakup) and/or aggregation (coalescence). It is of considerable interest to model a chemical process that occurs at the interface and therefore depends on the evolving size distribution of the dispersed phase. We apply distribution kinetics to represent the evolution of the dispersed-phase size distribution for simultaneous fragmentation and coalescence. The continuous phase with dissolved reactant enters and exits a continuous-flow stirred-Tank reactor. When the dispersed phase contained within the vessel satisfies a similarity solution, several rate expressions, including one for interphase mass transfer, that depend on mass moments of the size distribution allow analytical or simple numerical solutions. The solutions demonstrate how chemical reaction mass balances can be combined with distribution dynamics to extend chemical reaction engineering analysis. © 2003 by the authors. All rights reserved.