Ultra-fine fibrous PAAm hydrogel membranes were fabricated by electrospinning of aqueous solutions, followed by reaction with glutaraldehyde. A wide range of fiber diameters (267 nm to 2.8 mu m) and morphologies (beaded, round, branched and ribbon) could be achieved by PAAm molecular weight and solution properties. The optimally glutaraldehyde-crosslinked membranes were highly stable in water as well as in organic solvents (methanol, ethanol, acetone, chloroform, DMF and cyclohexane). Glutaraldehyde formed imine with PAAm amide side groups in the form of crosslinking bridges as well as grafts with hydrolyzed carboxylic end groups. The fibrous membrane showed excellent thermal stability, hydrophilicity, super water absorbency and exceptional tensile strength. The fibrous membrane exhibited excellent ability to entrap beta-galactosidase enzyme while allowing efficient diffusion of the substrate from and released products into surrounding media. The dual organic solvent and aqueous media compatible fibrous membranes have the promise for solid supported catalysis and diagnostic as well as a wide range of biomedical and industrial applications. (C) 2009 Elsevier Ltd. All rights reserved.