This study synthesized mixed matrix membranes (MMMs) using PEBAX® MH-1657 and ZIF-67 with varying particle concentrations (1, 3, and 5 wt%) to assess permeability and selectivity. ZIF-67 nanoparticles were prepared using the solvothermal method with methanol and characterized. Permeation tests were conducted at 10 and 15 bar using N2 and CO2. The analysis revealed ZIF-67 particles with an approximate diameter of 280 nm and confirmed characteristic sodalite peaks. The ideal CO2/N2 selectivity reached 67 (CO2 permeability = 132 ± 3.5 Barrer) at 15 bar. The impact of ZIF-67 varied with pressure and composition; at 10 bar, CO2/N2 selectivity decreased compared to pure PEBAX®; however, at 15 bar, the 1 wt% ZIF-67 membrane exhibited superior selectivity, surpassing Robeson's upper bound. The results indicate that ZIF-67 enhances the permeability and selectivity of PEBAX®, with superior performance observed at lower concentrations. MMMs (MMMs PEBAX MH1657 MH 1657 MH-165 ZIF67 ZIF ZIF-6 1, (1 3 wt characterized N CO2 CO 28 peaks CO2N2 CON CO2/N 6 (CO 13 35 3. Barrer composition however Robesons Robeson s bound MH165 165 MH-16 ZIF6 ZIF- ( 2 CO2N MH16 16 MH-1 MH1 MH-