This paper is based on the infinity/infinity analysis for the prediction of multiple steady states in multicomponent azeotropic distillation (Bekiaris et al., 1993). First, the quality of the prediction method is demonstrated by a brief review of an experimental verification separating a ternary azeotropic mixture. Then, the methods for prediction of multiple steady states are extended in two different directions. First, the existing method is combined with a singularity analysis to extend the predictions for specifications involving mass- or volumetric flowrates. Second, the infinity/infinity analysis is extended to reactive distillation systems involving equilibrium reactions using the transformation of Ung and Doherty (1995a) and the resulting reactive residue curves. Finally, the physical phenomena which cause the known multiplicities in the MTBE process are determined from this analysis and compared with available literature results.