A series of polysulfone-ferrosoferric oxide (Fe3O4) ultrafiltration membranes with different amounts of ferrosoferric oxide were prepared from suspensions using the phase inversion process. The suspensions consisted of polysulfone, N,N-dimethylacetamide, poly(vinylpyrrolidone), and ferrosoferric oxide. The results show that the pure water fluxes of membranes rise with increased concentrations of ferrosoferric oxide. However, the pure water fluxes were very low for membranes with ferrosoferric oxide concentrations below 47.4wt% and showed an abrupt rise in membranes with ferrosoferric oxide concentrations above 47.4 wt%. The rejection of membranes to bovine serum albumin showed an initial rise, then dropped with increased concentrations of ferrosoferric oxide. The membrane with 58.3 wt% ferrosoferric oxide displayed ideal comprehensive performances in pure water flux, rejection and antifouling ability. The pure water fluxes and the rejection of membranes can be explained by the cross-sectional structures of the membranes observed using SEM. (c) 2008 Elsevier B.V. All rights reserved.