The dynamic behavior of a batch distillation, column with a middle vessel is studied. A detailed mathematical model of a pilot-plant column is developed and validated against experimental data on a highly nonideal system; The simulated operation includes the column startup phase, during which the empty trays are sequentially filled with liquid from the top down. Then, the model is used to investigate the effect of different operating and design parameters on the column operability and productivity In particular, it is shown that restrictions exist in the choice of the column operating variables. These restrictions are related to both the total material balance and the component balance. Interactions between the operating parameters may result in unexpected responses of the plant. All the results make clear that the dynamic behavior of a complex batch column is not so easily understandable as the one of conventional batch rectifiers and batch strippers.