Three different types of titanium dioxide (TiO2) nanoparticles (P25, PC105 and PC500) with various sizes were applied for the preparation of mixed matrix polyethersulfone nanofiltration membranes. This work investigates the effect of types and sizes of TiO2 on the morphology, performance and fouling control of nanofillers embedded membranes. The membrane characterization was carried out by FFIR, XRD, EDX, contact angle, surface and cross-section SEM images and pure water flux measurements. The surface hydrophilicity of the TiO2 blended membranes was improved due to water affinity improvement of the membrane surface. The high content of PC-105 and PC500 TiO2 nanoparticles in the casting solution diminished membrane performance due to the agglomeration of these nanoparticles in polymer matrix. However, the P25 nanofillers showed better dispersibility. The antibiofouling performance of the membranes fouled by whey solution was investigated by measuring fouling resistance parameters. The nanofiltration membranes made from the nano-sized TiO2 particles elevated the pure water flux and antifouling properties. Flux recovery percentage of the nascent PES membrane was increased from 56 to 91% by blending 4 wt.% P25 nanoparticles. At low concentration of TiO2, the nanoparticles with small size caused more biofouling reduction due to this fact that the aggregation of the nanoparticles was not prominent at low amount. (C) 2012 Elsevier B.V. All rights reserved.