A highly tough ionic liquid (TL)-based gel membrane with a specific inorganic/organic composite network is fabricated. Owing to the inorganic/organic composite network, the composite ion gel membrane with 80 wt % Of IL shows excellent pressure resistance. The mechanical and gas permeation properties of the composite ion gel membrane can be controlled by changing the inorganic/organic network composition as well as the cross linking degree of the organic polymer network. Although the mechanical and gas permeation properties show a trade-off relationship with the normal ion gel, the composite ion gel membrane, which has a relatively low composition of loosely cross linked organic polymer network, exhibited not only high CO2 permeability but also high mechanical strength. The composite ion gel membrane with an optimized network Composition achieved CO2 permeability of approximately 150 barret and a CO2/N-2 selectivity of 20 for more than 300 hat 50 degrees C under humid conditions.