Mg(OH)(2)/PES (magnesium hydroxide/polyethersulfone) hybrid membranes were prepared by in-suit synthesized phase inversion method. The highlight of this method is that it affords uniform distribution of Mgt(2+) on an atomic level in the casting solution, reacted with OH-in the coagulation bath during the formation of membrane via phase inversion process, and nano-sized Mg(OH)(2) was in-suit formed and distributed uniformly in PES matrix. SEM, XPS and BET analysis were performed to characterize the membranes, and ultrafiltration properties were investigated and compared. The results indicated that all the tested performance of the PES membranes was generally improved by the existence of Mg(OH)(2). Additionally, with the increase of MgCl26 center dot H2O, the surface hydrophilicity, porosity, and permeation flux improved proportionally, while EA retention rate and antifouling property increased firstly and then decreased. It is suggested that this research will provide a new line for the preparation of homogeneous organic-inorganic membranes. (C) 2016 Elsevier B.V. All rights reserved.