Abstract In the context of post-combustion carbon dioxide capture, the existence of the Metal-Organic Framework (MOF) transparency effect, which can enhance carbon dioxide uptake under humid conditions, was recently demonstrated. It is, therefore, essential to first determine the water adsorption capacity within the MOF. In this work, the CAU-23 MOF material, which appears to possess the main chemical and structural characteristics necessary for MOF transparency to occur, was considered. In addition, Mixed Matrix Membrane (MMM) is now considered on an industrial scale for shaping purposes. Among polymers, the intrinsically microporous polymer PIM-1 has shown interesting adhesion properties with MOF surfaces. Thus, before investigating what happens within the MMM, we aim to examine the water adsorption within the bulk CAU-23 and PIM-1 materials using the recently developed osmotic molecular dynamics simulations. These preliminary results show that CAU-23 could be a promising material for enhancing the MOF’s transparency and increasing $$\hbox {CO}_2$$ CO 2 uptake. Graphic abstract