We develop feasibility criteria for reactive distillation systems in terms of phase and reaction equilibria. A reactive distillation column with the liquid-phase reaction R1 + R2 <----> P1 can be feasible if the feed composition, the pseudo-feed composition, and the reaction difference point lie on a single straight line. In addition to this material balance constraint, the liquid composition vectors starting from the given top product composition should lie within or move toward the forward reaction region as well as lie within or move toward the reachable region from the bottom product of the nonreactive stripping section. We also perform feasibility studies on reactive distillation with the reaction 2R1 <----> P1 + P2 in terms of the normalized product and reactant coefficient vectors. For these ternary reaction systems, the larger the reflux, the greater the reaction conversion. We finally propose several feasible flowsheets for the methyl tert-butyl ether production system.