Polycarbonate (PC) membranes with high tearing stress and porosity could be prepared in supercritical CO2. Effect of polyethylene glycol (PEG) concentration, membrane thickness, temperature, and pressure on the membranes were investigated. The porous membrane was prepared at inversion conditions of 15 MPa pressure, 45degreesC temperature, and over 20 min, to enhance both porosity and tearing stress. Porosity of 10 mum thickness membrane was 72% and was 70, 67, 66, and 62%, respectively, with an increasing membrane thickness in 20, 30, 40, and 50 mum. The tearing stress with 62% porosity was 390 g cm(-1) and increased from 398 to 478 g cm(-1) with an increasing porosity from 66 to 72%. It was observed that the relationship between porosity and tearing stress was close and porosity should increase in order to enhance tearing stress of the polycarbonate membrane with porous structure. (C) 2004 Elsevier B.V. All rights reserved.