Polymer solutions of polysulfone (PSf) and methylcellulose (MC) in 1-methyl-2-pyrrolidone (NMP) were used to prepare ultrafiltration membranes by the phase inversion technique via immersion precipitation. The effect of MC additive on the structure and performances of the membranes was studied. The obtained membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), infrared spectroscopy (FTIR-ATR), equilibrium water content (EWC), water contact angle, porosity and ultrafiltration experiments of polyethylene glycol solutions. It was found that all the PSf/MC membranes had higher porosity, more hydrophilic surface and more vertically finger like pores than PSf membrane. With an increase in MC content in the casting solution from 0.5% to 1.5%, the hydraulic permeability increases from 17.17 to 118.46 L.m-2.h-1.bar-1, while the rejection decreases from 91.82% to 64.45% with PEG 35000. DSC scan and FTIR analysis confirmed that methylcellulose was trapped in the membranes matrix.