This work investigated the effect of variation in polyamide structure of thin film composite nanofiltration membranes resulting from variation in monomers on flux and rejection properties. Membranes from various combinations of monomers have been prepared including mixture of diamines or acid chlorides. The physicochemical characteristics of the membranes thus obtained were determined by infra-red spectroscopy, SEM, AFM, contact angle measurement and molecular model analysis. Attempts have been made to correlate the observed flux and rejection properties of the membranes with their physicochemical properties. It has been observed that polyamide structure influences flux and rejection of membranes to a great extent. (c) 2009 Elsevier B.V. All rights reserved.