Both zeolite 5A filled and unfilled, crosslinked polyvinylalcohol (PVA)/polyethyleneglycol (PEG) blend membranes were synthesized and characterized for CO 2/CH 4 separation. The polar ether segments of PEG interact favorably with CO 2, thus resulting in a high solubility selectivity, while PVA provides a mechanically strong polymer matrix. The crosslinking time, molecular weight of PEG and PEG (MW 200) content were found to significantly affect the gas transport property of resulting membranes, including gas permeability and CO 2/CH 4 selectivity. At 64 wt.% PEG (MW 200), the membranes showed good CO 2 permeability of 80.2 Barrers (1 Barrer = 10 −10 cm 3 (STP) cm/cm 2 s cmHg) and CO 2/CH 4 selectivity of 33 at 30 °C. Effects of the zeolite 5A loading, temperature and feed pressure were investigated for the gas separation performance of both zeolite-filled and unfilled PVA/PEG membranes. It was found that CO 2/CH 4 selectivity decreased as the zeolite 5A content increased, while CO 2 permeability first decreased and then drastically increased. Increasing temperature enhanced CO 2 permeability but sacrificed their selectivity for both zeolite-filled and unfilled PVA/PEG membranes. As temperature decreased, the unfilled PVA/PEG membranes could perform beyond the Robeson's upper bound. Compared to the unfilled PVA/PEG membrane, the zeolite-filled PVA/PEG membrane showed improved performance as feed pressure increased.