In this paper, rigorous modelling of reactive separations is considered. Focus is set to gas/vapour-liquid systems, namely reactive distillation and reactive stripping. The paper describes the modelling framework and the process simulator PROFILER developed within the European research project Intelligent Column Internals for Reactive Separations (INTINT). The application is illustrated by two heterogeneously catalysed esterification processes: the synthesis of ethyl acetate from ethanol and acetic acid via reactive distillation and the synthesis of octyl hexanoate from octanol and hexanoic acid via reactive stripping. For both processes, the simulation results are in satisfactory agreement with the experimental data. A comparison of different model complexities is presented. (c) 2004 Elsevier B.V. All rights reserved.