A new H2O2 biosensor was constructed by immobilizing Hb in the Chit-MWNTs/Au@Au2S2O3 composite membrane. Owing to the superior performance of novel Au@Au2S2O3 core-shell nanomaterials and its synergy with multi-walled carbon nanotubes (MWNTs), the direct electron transfer of Hb in composite membrane was easily achieved. The Chit-MWNTs/Hb/Au@Au2S2O3/CCE displayed a pair of well-defined and reversible redox peaks in 0.1 M pH 7.0 PBS. The electrocatalytic reduction to H2O2 of Chit-MWNTs/Hb/Au@Au2S2O3/GCE was also studied. Its apparent Michaelis-Menten constant for H2O2 was 0.014 mM, showing a good affinity. The experimental results showed that the linear dependence of the biosensor was from 4.0 x 10(-5) to 7.2 x 10(-4) M, and the detection limit of the sensor was 3.2 x 10(-6) M (S/N = 3). Moreover, the biosensor showed a rapid response to H2O2, a good stability and reproducibility. (C) 2012 Elsevier Ltd. All rights reserved.