CEMCAP is an international R&D project under the Horizon 2020 Programme preparing the ground for the large-scale implementation of CO₂ capture in the European cement industry. This paper concerns the performance modeling of membrane-assisted CO₂ liquefaction as a possible retrofit application for post combustion CO₂ capture. For the relatively large CO₂ concentrations that are typical for the flue gas in conventional cement kilns, it may be possible to capture CO₂ by combining a single membrane unit for bulk separation and a CO₂ liquefaction train in which the waste stream is recycled and mixed with the feed to the membrane system. The required membrane surface area is strongly correlated with the CO₂ concentration in the cement kiln flue gas, as well as targeted CO₂ recovery, pressure ratio across the membrane, membrane separation factor and CO₂ permeance. Specifications for flue gas pre-conditioning and an overall techno-economic evaluation are planned to follow the evaluation of experimental results for membrane performance under realistic conditions, as well as for CO₂ liquefaction performance. Published by Elsevier Ltd.