Polyethersulfone (PES) hollow fiber membrane was prepared by blending with nonionic surfactant Tectronic 1307 to improve its hydrophilicty. The membranes were posttreated by hypochlorite solution of 10, 100, 500, and 2000 ppm. The effect of hypochlorite treatment on the performance of PES membrane was investigated. Experimental results showed that the water permeability of treated membrane was two to three times higher than that of untreated membrane in case of blend membrane prepared from PES/N-methyl-2-pyrrolidone (NMP)/Tectronic 1307 solution. On the other hand, hypochlorite treatment was no effect on eater permeability of the membrane prepared from PES/NMP solution. Elemental analysis and ATR-FTIR measurement results indicated that hypochlorite treatment led to decomposition and leaching out of Tectronic 1307 component from the membrane. The change of membrane surface structure by the hypochlorite treatment was confirmed by atomic force microscopy measurement. The hypochlorite treatment brought about no significant impact on the mechanical property of the membranes. This indicated that the hypochlorite treatment of PES membrane prepared with surfactant was a useful way to improve the water permeability without the decrease of membrane strength. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110:687-694, 2008