Cellulose acetate (CA)/graphene oxide (GO) nanocomposite membranes were generated by an assisted phase inversion process, based on the use of SC-CO2, as nonsolvent, operating at 200 bar and 40 degrees C; loadings of GO up to 9% w/w were tested. The structures maintained the cellular morphology, characteristics of CA membranes, also at the highest GO loadings used, with a porosity of about 80%, but the presence of GO influenced the pore sizes, that ranged between about 9 and 16 mu m. The starting GO and the nanocomposite structures were characterized by the combination of various techniques that evidence as sulfur and chlorinated impurities, that were present in the starting GO material, were completely eliminated by the interaction with SC-CO2 during structures formation; moreover, a partial reduction of GO to graphene was also observed.