This work deals with the incorporation of deca-dodecasil 3 rhombohedral (DD3R) zeolite as an inorganic filler into the Pebax (R)-1074-based polymer matrix to enhance the performance of the pure polymeric membrane in CO2/CH4 separation. The membranes were fabricated with different concentrations of DD3R. Separation performances of the membranes were investigated at various feed pressures and temperatures. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) analysis of the prepared membranes were performed. In the best case, selectivity for CO2/CH4 separation was improved, while the permeability decreased. Membranes with 1 and 5wt% DD3R were located in the acceptable region beyond the Robeson plot (1991) for CO2/CH4 gas pairs.