BACKGROUND: Forward osmosis (FO) membranes need to be improved since water fluxes of commercial FO membranes are low. Using electrospun polysulfone (PSf)/titanium dioxide (TiO2) nanocomposite fibers as substrates could be a good way to make high-quality FO membranes. The effect of nano-TiO2 on polyamide thin film nanocomposite (TFN) FO membrane was investigated. The nanocomposite substrates were fabricated by electrospinning. Hydrophilicity, porosity, pore size and mechanical properties of themembranes were determined. RESULTS: Results indicated that hydrophilicity, porosity and pore size of the substrates were increased upon addition of TiO2. Water flux of TFN membrane prepared using PSf substrate embedded with 0.25wt% TiO2 nanoparticles (denoted as TFN 0.25) was improved by 19% compared with controlled TFC membrane. Further increase in TiO2 nanoparticles loading to 0.5 and 0.75wt% had higherwater flux, but their FO performanceswere compromised by a significant increase in reverse solute flux and the active layer is more vulnerable. FO performance evaluation indicated that TFN 0.25 membrane showed the most promising results, with high water flux and low reverse solute flux. CONCLUSION: This study demonstrated that PSf/TiO2 solution can be electrospun as substrate to make TFN membranes with higher water flux than commercial membranes and electrospun membranes without nano-TiO2. (C) 2017 Society of Chemical Industry