Asymmetric ultrafiltration (UF) membranes were prepared from poly (ether sulfone) (PES) using N,N'-dimethylformamide (DMF) solvent by phase inversion method. Solution cast PES membranes were homogeneous for all studied compositions, 12.5 to 20% polymer and 87.5 to 80% of solvent. The fabricated membranes were characterized for their UF performance such as pure water flux, water content and membrane hydraulic resistance and found to be moderate changes. It is estimated that the pure water flux of 20% PES membrane increases from 12 to 76 L/m2.h, when the polymer concentration was decreased to 12.5% in the casting solution. The membranes were also characterized for their separation performance through metal ions in aqueous solution. The percentage rejection of metal ions was increased while the permeate flux has decreasing trend.