Two important issues in application of ultrafiltration (UF) membrane, i.e. study of fouling mechanism and synthesis of low fouling membrane have been performed. Study on fouling mechanism was done by investigation of membrane-solute interactions (static adsorption) and membrane-solute-solute interactions (UF) using dextran and myoglobin as the model for polysaccharide and protein, respectively. Low fouling UF membranes have been synthesized by photograft copolymerization of water soluble monomers, poly(ethylene glycol) methacrylate (PEGMA) and N,N-dimethyl-N-(2methacryloyloxyethyl-N-(3-sulfopropyl) ammonium betaine (SPE), onto polyethersulfone (PES) membrane with and without cross-linker monomer N,N'-methylene bisacrylamide (MBAA). Commercial polyethersulfone (PES) and cellulose-based UF membranes were used during fouling mechanism study whereas two commercial PES UF membranes with different nominal cut-off were used as the base membrane upon surface modification.In both studies, the membranes were characterized with respect to the membrane chemistry (by IR-ATR spectroscopy and elemental analysis), surface wettability (by contact angle), surface charge (by zeta potential) and pure water permeability, pore structure and surface morphology (by hydraulic permeability and rejection measurements, scanning electron microscopy, and atomic force microscopy). In addition, in the fouling mechanism study, quantification of solute attached on the membrane surface was performed by simultaneously diffusion adsorption measurements (SDAM).