This paper describes a rate-based parallel column model, which, via the CAPE-OPEN framework, can be used in any CAPE-OPEN compliant process flowsheet simulation package and can be used to model dividing wall columns of arbitrary configuration. Heat transfer across the dividing wall can be modelled in a straightforward way. Vapour split ratios are determined during the solution of the model equations by requiring the pressure on both sides of the dividing wall(s) to be equal. We compare the predictions of the rate-based model to experimental data from the University of Texas at Austin. There is good agreement between model and measured data. A design case study demonstrates the versatility of our method of calculating vapour splits from a pressure balance. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.