Catalases decompose hydrogen peroxide (H2O2) into water and oxygen in an effective and environmentally friend way. The decomposition of H2O2 by nanofibrous membrane-supported catalases is reported in this work. Poly(acrylonit.rile-co-N-vinyl-2-pyrrolidone) (PANCNVP) and polyacrylonitrile (PAN) blending with or without multi-walled carbon nanotubes (MWCNTs) were electrospun into nanofibrous membranes as enzyme immobilization matrixes and were carefully characterized. To immobilize catalase covalently, the nanofibrous membranes were treated with alkali solution to generate carboxyl groups followed by activation procedure with EDC/NHS. Results indicate that the nanofibrous membranes can bind large amount of catalases due to their superior surface area to volume ratio. The decomposition behavior of H2O2 with these immobilized catalases was explored. The increment of activity retention induced by the NVP moieties and/or MWCNTs is remarkable. Stabilities of the immobilized catalases including the effects of substrate pH and reaction temperature, thermal stability, operational stability and storage stability were also carefully studied. Results elucidate the improved stabilities of the nanofibrous membrane-supported catalases. In conclusion, the nanofibrous membranes electrospun from this biocompatible polymer, especially those filled with MWCNTs, are suitable matrices for catalase immobilization. (c) 2007 Elsevier Inc. All rights reserved.