Graphene and its derivatives have got numerous exciting applications due to the monolayer of Lightly packed carbon atoms that possess many interesting properties. In this work, as-prepared graphene oxide (GO) was modified by hyperbranched polyethylenimine (HPEI) and then blended into polyethersulfone (PES) casting solution to prepare PES ultrafiltration membrane via phase inversion method. GO and its modified products were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The morphology and performance of the hybrid membranes were characterized by scanning electron microscopy (SEM), TEM, water contact angle, permeation measurement, mechanical measurement, antifouling and antibacterial tests. Mechanical tests revealed that the hybrid membranes exhibited a higher tensile strength and Young's modulus. The hybrid membranes exhibited a slightly lower pure water flux compared with pure membranes; however, the antifouling tests revealed that the hybrid membranes blended with HPEI-GO nanosheets displayed a preferable antifouling performance. The antibacterial tests confirmed that the as-formed hybrid membranes showed an effective antibacterial performance against Escherichio coli (E. coli). (c) 2013 Elsevier B.V. All rights reserved.