Forward osmosis (FO) process has attracted increasing interest because of its potential applications for low-energy desalination. However, the internal concentration polarization (ICP) has been considered as one of the key issues that can significantly reduce the water flux across the FO membrane. In this paper, we report the preparation of polyethersulfone (PES)/multiwalled carbon nanotube (MWCNT) substrate for the formation of a high-performance FO membrane. Nanocomposite MWCNT/PES substrates were obtained by dispersing carboxylated MWCNTs within PES via solution blending, and subsequent phase inversion process; The FO membranes were then prepared by depositing a polyamide active layer in-situ on the MWCNT/PES substrate with a finger-like macrovoid structure. The influence of addition of MWCNTs on morphology and properties of substrates and final FO membranes was systematically investigated. The results show that the performance of the FO membranes with MWCNT/PES nanocomposite substrates is better than that of the commercial membrane. Furthermore, the tensile strength of the substrate with MWCNTs is also greater than that of the neat PES. This work indicates that the FO membranes prepared from MWCNT-PES substrates are promising for practical FO applications. (C) 2013 Elsevier B.V. All rights reserved.