A novel silver sulfide nanospheres anchored multiwalled carbon nanotubes (Ag2S-MWNTs) nanocomposite was prepared by hydrothermal method, after which the direct electrochemistry of hemoglobin (Hb) immobilized on the Ag2S-MWNTs/chitosan (Ag2S-MWNTs/CHIT) composite matrix modified glassy carbon electrode (GCE) was demonstrated. The morphologies and composition of the Ag2S-MWNTs were characterized by transmission electron microscopy and energy dispersive X-ray spectroscopy. Cyclic voltammetric and amperometric studies demonstrated that the Hb incorporated in the Ag2S-MWNTs/CHIT film exhibited a pair of well-defined, quasi-reversible cyclic voltammetric peaks at about -0.30 V vs. SCE in pH 7.0 buffer and possessed excellent electrocatalytic ability toward H2O2 reduction. The linear dynamic range for the detection of H2O2 was 0.8 - 240.0 mu M with a correlation coefficient of 0.999 and the detection limit was estimated at about 0.4 mu M (S/N = 3). The electron transfer rate constant was estimated to be 3.1 . s(-1), suggesting a fast direct electron transfer was realized. The present study indicated that the nanocomposites show the potential applicability as the new type of mediator for direct electrochemistry of the redox proteins. (C) 2015 The Electrochemical Society.