Blending of various polymers has stimulated great interest in membrane science to improve the performance of membranes such as hydrophilicity and flux and to reduce the fouling behavior. In this study, ternary blend membranes were prepared with cellulose acetate (CA), polysulfone (PSf), and sulfonated poly(ether ether ketone) (SPEEK). The prepared membranes were characterized in terms of compaction, pure water flux, membrane hydraulic resistance, and water uptake. With the increase of SPEEK component from 0 to 15 wt % in the ternary blend mixture, pure water flux increased from 31 to 91 L m(-2) h(-1). The pore size and porosity of the membranes increased with increasing concentrations of SPEEK as revealed by pore statistics and molecular weight cutoff (MWCO) studies using different molecular weights of dextrans. MWCOs of the membranes ranged from 19 to 150 kDa, depending on the various polymer blend compositions. Cross-sectional images from scanning electron microscopy showed larger macropores in the bottom layer of the membranes with increasing SPEEK content. Observations from scanning electron microscopy provided qualitative evidence for the trends obtained for permeability, pore statistics, and MWCO results.