Poly(vinyl alcohol)-polyethylene glycol, PVA-PEG, blended membrane were prepared using supercritical fluid assisted phase-inversion method, in which scCO(2) was used as the anti-solvent. Poly(vinyl alcohol) was utilized as the main polymer, polyethylene glycol as the additive, and dimethyl sulfoxide (DMSO) as the solvent of these polymers. Taguchi method was used to investigate the effect of some operating parameters on the morphology of the membranes. The L16 orthogonal array was selected under the following conditions: pressure (100, 135,165 and 200 bar), temperature (40, 45, 50 and 55 degrees C) and PEG weight percent (0, 0.33, 0.66, and 1%). Total polymer concentration of solutions in all experiment was constant at 10% (w/w). The morphology of the obtained porous membranes was characterized by scanning electron microscopy. Through changing the conditions in each experiment, the average pore diameter changed between 3.75 and 12.2 mu m. Results from analysis of variance (ANOVA) indicate that PEG concentration was the most significant factor on the average pore size of prepared membranes by 78.7%. This is the first work announcing preparation of PVA-PEG membrane using supercritical CO2. (C) 2014 Elsevier B.V. All rights reserved.