We present a visual-aided method to carry out stage calculations of a reactive distillation column with the ternary isomolar reaction, 2R1 <-> P1 + P2. The reactive cascade different point, which is the combined point of stoichiometric coefficient vectors and product compositions, enables us to step off or up the stages. For a given reflux or reboil ratio, we can determine the extent of reaction on each reactive stage in terms of a reaction equilibrium curve and a bubble point curve equilibrated with the reaction equilibrium manifold. if tho reaction equilibrium curve lies to the left of the bubble point curve for a liquid phase reaction, the stripping section with the reactive feed stage is better than the reactive rectifying section with the reactive feed stage in terms of reaction conversion and separation efficiency. (C) 2000 Elsevier Science Ltd. All rights reserved.