Novel thin-film nanocomposite (TFN) membranes were fabricated by incorporation of Magnetite/Zinc oxide (Fe3O4/ZnO) nanocomposite for the forward osmosis (FO) processes. Different concentrations of Fe3O4/ZnO nanocomposite (0.1, 0.2 and 0.3 wt%) were added to the sublayer and also 0.02 wt% of Fe3O4/ZnO nanocomposite was added to the active layer. The prepared TFN membranes were characterized with aspects to membranes surface and structure properties, separation properties and also FO membrane performance and subsequently compared with thin-film composite (TFC) membrane. The hydrophilicity of TFN membranes surface was improved with increasing Fe3O4/ZnO in the casting and aqueous solution due to the activation of Fe3O4/ZnO nanocomposite under UV light irradiation. Compared to the TFC membrane, the TFN FO membrane water flux was reported to increase remarkably from 16.5 to 29.3 L/m(2) h (10 mM NaCl as feed water (FW)) and 14.5 to 27.2 L/m(2) h (Acarbose solution as FW) when 2 M NaCl salt was utilized as draw solution (DS). The improvement in FO water flux was ascribed to the lower S parameter of modified PES sublayer and the decline of internal concentration polarization (ICP). Long-term experiments demonstrated that the modified FO membranes had lower flux reduction compared to control TFC FO membrane. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.