Polypropylene membrane with 71% porosity was prepared for PEMFC because of its low cost and easy handling. The pores and porosity were controlled by altering the polypropylene concentration and extraction rate of camphene from the membrane in supercritical CO2. The average pore size in the membrane was about 2~3 μm and the porosities were 80, 76, and 71% with 10, 20, and 30 polypropylene wt% respectively. The breaking points of the polypropylene membrane with 10, 20, and 30 polypropylene wt% were 0.17, 0.24, and 0.46 Kgf/mm2, respectively. The optimum conditions for the camphene extraction were performed at 45℃ and 150 bar for 10 min. The thickness of the polypropylene membrane was 70±3 μm and the composite membrane impregnated with Nafion® solution was 105±3 μm. The water uptake and ion conductivity of the polypropylene composite membrane were 25±3% and 0.0030±0.0005 S/cm, respectively.