The development of MWCNT mixed matrix membranes (MWCNT-MMMs) has shown good performance for gas separation. Interfacial interactions between the multi-walled carbon nanotubes (MWCNTs) and the polymer and the dispersion of the MWCNTs in the polymeric matrix affect the overall performance of MWCNTs mixed matrix membranes. Although MWCNTs properties are superior to other inorganic fillers but due to their chemically inert properties and inability to disperse in typical organic solvents, their applicability in industry is still uncertain. Generally, nanotubes are bundled tightly together by strong van der Waals interactions. Therefore, MWCNTs tend to accumulate to each other in polymer matrix. This has been the biggest challenge in the development of MWCNT-MMMs for producing membranes free of defects. In this research, PES/Pebax-MWCNTs mixed matrix membranes were fabricated to capture CO2 from natural gas. Sorbitol has been utilized in the fabrication of membranes to break the agglomeration of MWCNTs. In this study, the effect of MWCNTs loading and addition of sorbitol on the structure of synthesized membranes was analyzed using FESEM, DSC and FTIR. The incorporation of MWCNTs in the polymer matrix allows more active path for small molecules to flow across the membranes. The agglomeration of MWCNTs is more significant with the increase of fillers loading. Addition of sorbitol improved the morphology of membranes. Smooth surface of membranes with no agglomeration are observed for all MWCNTs loading (2-6 wt). Glass transition temperature (Tg) was shifted to lower temperature with the addition of both MWCNTs and sorbitol. © 2022 Trans Tech Publications Ltd, Switzerland.