Novel asymmetric microporous polyethersulfone (PES)/polysulfide-amide (PSA) blended ultrafiltration membranes with superior properties were prepared using the phase inversion induced by immersion precipitation method. The hydrophilic PSA copolymer with nitro groups, thiazole rings, and thioether linkages was synthesized via phosphorylation polycondensation. Different concentrations of the copolymer were used in the PES casting solutions for improving membrane properties and the results were compared with polyvinyl pyrrolidone (PVP)/PES membrane. The presence of amide band, correlated with the stretching vibration of the carbonyl group and bending vibration of NH group on the ATR-FTIR spectra of the modified membranes confirmed the existence of PSA in the PES membrane structure. The cross-section SEM images showed that the membranes with lower skin layer thickness were formed by addition of PSA in the casting solution. Not only the pure water and BSA solution flux of the blended membranes were increased by enlarging PSA concentrations in the casting solutions up to 2% PSA, but also antifouling properties were improved. Comparing PSA with PVP additive showed that the PSA could improve membrane hydrophilicity, porosity, permeability and antifouling properties. However, the PVP has better performance in case of the porosity and the permeability improvement. Therefore, for coupling of the effect of these two additives, the membrane with 1 wt% PVP and 1 wt% PSA was prepared. The results showed that the prepared membrane had good solution flux with good antifouling properties. (C) 2016 Elsevier Inc. All rights reserved.