In this study, polyacrylonitrile (PAN) nano-fibrous membranes with fiber diameters of similar to 450 nm were prepared by the technique of electrospinning; amidoxime nano-fibrous membranes were then prepared through treatment of PAN nano-fibrous membranes in hydroxylamine (NH(2)OH) aqueous solution. The -C N groups on the surface of PAN nanofibers reacted with NH(2)OH molecules and led to the formation of -C(NH(2))= N-OH groups, which were used for coordination of Ag(+) ions. Subsequently, the coordinated Ag(+) ions were converted into silver nanoparticles (AgNP) with sizes being tens of nanometers, morphologies, structures, and antimicrobial efficacies (against Staphylococcus aureus and Escherichia coli) of the membranes of electrospun PAN (ESPAN) nanofibers, ESPAN surface functionalized with amidoxime groups (ASFPAN), ASFPAN coordinated with silver ions (ASFPAN-Ag(+)), and ASFPAN attached with silver nanoparticles (ASFPAN-AgNP) were investigated. The study revealed that, with treatment of ESPAN membranes in 1 M NH(2)OH aqueous solution for 5 min, the resulting ASFPAN membranes became antimicrobial without distinguishable morphological variations; further treatment of ASFPAN membranes in 0.1 M AgNO(3) aqueous solution for 1 h and the subsequent treatment in 0.01 M KBr aqueous solution for 2 h followed by photo-decomposition made the respective membranes of ASFPAN-Ag(+) and ASFPAN-AgNP highly antimicrobial, which were capable of killing the tested microorganisms in 30 min. The water permeability test indicated that these membranes possessed adequate transport properties for filtration applications. This study demonstrated a convenient and cost-effective approach to develop antimicrobial nano-fibrous membranes that are particularly useful for the filtration of water and/or air. (C) 2010 Elsevier B.V. All rights reserved.