The immobilization and electrochemical behaviors of cytochrome c on a NaY zeolite modified electrode were studied. The interaction between cytochrome c and NaY zeolite particles was examined by using UV-Vis spectroscopy and electrochemical methods. The direct electron transfer of the immobilized cytochrome c exhibited a pair of redox peaks with the E-1/2 of -(44 +/- 3) mV (versus SCE) in 0.1 M pH 7.0 PBS. The electrode reaction showed a surface-controlled process with a single proton transfer at the scan rate range from 20 to 500 mV s(-1). Based on the immobilization of cytochrome c on NaY zeolite a high performance biosensor was constructed, which displayed an excellent response to the reduction of hydrogen peroxide (H2O2) without the aid of an electron mediator and could be used for H2O2 detection. NaY zeolite provided a good matrix for protein immobilization and biosensor preparation. (C) 2004 Elsevier Ltd. All rights reserved.