A new software tool to simulate and optimise processes that combine distillation column with a reactor sequence has been developed. This kind of combination is particularly interesting when new intensified and integrated processes are developed. The unit block contains both the distillation column model and the models for the coupled reactors. The model equations are solved simultaneously in one block and not sequentially as it is done when the reactor/distillation systems are solved by present flowsheet programs. This software module has been implemented into a flowsheet simulator environment that contains all required physical and chemical data banks and enables large-scale process optimisation. The applicability of the new module is demonstrated by solving two presently interesting processes: production of MTBE and isooctene. The model has shown good convergence properties.