This article demonstrates the usefulness of a graphical approach the residue curve method - in a preliminary feasibility study of a reactive distillation process. First, we refine a calculation for generating the residue curves for a multicomponent system in which one or more chemical reactions can occur. These residue curves give both a precise idea of whether there are distillation barriers and the limits to separation by distillation. Then, analyzing the curves, we derive a method for evaluating the feasibility of reactive distillation. Starting with a fixed-composition feedstock (F), we define a range within which the products will be found. Conversely, to achieve a given product purity, we determine the limits within which the feedstock composition-must fall. A practical example, the conversion of isobutene into ether by methanol in the presence of inert material, is presented.