Molecularly imprinted composite membranes for selective binding and permeation of S-Naproxen (S-Nap) were synthesized using the copolymerization method with 4-vinyl-pyridine (4-VPy) as functional monomers and ethylene glycol dimethacrylate (EDMA) as cross-linkers. The characterization results showed that, the binding constant (K) for the formation of monomer-template adduct was 13.8 M-1 by means of infrared spectroscopy and nonlinear least-squares method. And the scanning electron microscope was used to visualize surface and cross-sections of membranes to gain better understanding in the analysis of imprinted layer deposited on PVDF Support membranes. The separation property of the imprinted membrane was determined by on-line HPLC membrane separation technology. The separation mechanism of the S-Nap imprinted membrane could be defined as facilitated permeation mechanism. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.