In this paper, a newly designed distillation column consisting of a wetted wall with a rectangular cross section is analyzed and compared with a conventional packed column with regard to the operating range of both apparatuses. As expected, the pressure drop is considerably lower in the wetted-wall column and, therefore, it offers a higher range of operation. However, in the wetted-wall column, the separation efficiency decreases rapidly with increasingF factors. This effect can be overcome by the serial connection of two wetted-wall columns.