In this work the effect of chlorination on the change of hydrogen bonding behavior and performance of crosslinked aromatic polyamide membrane has been systematically investigated. Chlorination replaced hydrogen with chlorine on the amide group of the membrane polymer and caused the loss of hydrogen bonding sites, confirmed by the systematic shift of the amide I band (C=O stretching vibration) to the higher wavenumbers and the disappearance of the amide II band (N-H bending vibration) by FF-IR spectrum analysis. Performance experiments demonstrated that the change of hydrogen bonding behavior due to the chlorination caused the change of flexibility of polymer chains followed by the change of initial flux and subsequent flux change with filtration time. (c) 2006 Elsevier B.V All rights reserved.