Due to the important role of thermal membrane separation processes for the chemical industry, simulation of those process steps is more and more relevant. In the simulation software AspenPlus(C) no unit operation for a membrane distillation step is available. Due to the lack of built in membrane distillation (MD) models, the aim of this work was to develop one for application in conceptual design on the AspenPlus(C) platform. Therefore, this paper presents a user-customize one dimensional unit operation for vacuum MD on the basis of the dusty gas model. Binary butanol water mixtures of different concentrations served as feed streams. Experimental investigations on a hollow fibre and tubular polypropylene (PP) membrane module with a pore diameter of 0.2 mu m resulted in raw data on transmembrane flux and selectivity. These experiments served to generate a component permeance data bank. On the basis of the results, a regression for the component permeance was performed. The implementation of the generated permeance functions in the programming code resulted in a unit operation in AspenPlus(C) reproducing well the experimental work. Comparison of the model with the laboratory results show very good reliability for the different membranes investigated. (C) 2014 Elsevier B.V. All rights reserved.