By using phase and reaction equilibrium information, the feasibility criteria for single-feed and double-feed reactive distillation systems are derived: When the products are a stable node and an unstable node and a part of the reaction equilibrium curve lies in the same distillation region as the products, both reactive rectifying and reactive stripping sections can feasibly produce pure products in a single-feed column. If one of the products is a saddle and no azeotrope exists between the products, a single-feed column is still feasible, but only with large reaction equilibrium constants. If a saddle product forms a minimum-boiling azeotrope with another product, an entrainer is needed to break this azeotrope in a double-feed column. If both reaction products are saddles, the same double-feed column configuration with an entrainer can produce pure products.