Nanofiltration (NF) is known as a very effective technology in the removal of micropollutants from surface water for drinking water purposes. In this study, NF of triclosan (TCS) which is a commonly used biocide in many different domestic and industrial applications was investigated in relation to its interaction with natural organic matter (NOM). A laboratory scale cross-flow device was operated in total recycle mode using a thin-film composite membrane with a real surface water. The effect of NOM content on TCS removal was elucidated through addition of humic acid (HA) into raw water. The performance of the membrane was evaluated by TCS retention, as well as flux behavior. The results showed that NOM had a positive effect on TCS removal due to TCS-HA complex formation that limits TCS permeation through the membrane. On the other hand, NOM was found to increase Molecular weight cut off (MWCO), but not resulting in a decrease in TCS rejection due to HA-TCS complex formation. NOM lead to an increase in TCS removal mainly by sorption into the membrane. (C) 2015 Elsevier B.V. All rights reserved.