Au nanoparticles (NPs) decorated Graphene (Gr) composites were prepared by the reducing agent-free microwave-assisted hydrothermal techniques and employed to immobilize hemoglobin (Hb) to fabricate a novel biosensor. The Au nanoparticles decorated graphene sheets (Au NPs-Gr) composites were characterized by the X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), Raman spectra and scanning electron microscopy (SEM). Meanwhile, the electrochemical properties were investigated by the cyclic voltammograms (CVs) and amperometric current-time method. The experimental results demonstrated that Au NPs with the diameter of 20 nm were uniformly bestrewed and not aggregated on the surface of the Gr sheets. The resulting biosensor displayed a high sensitivity, good reproducibility, long-time stability, wide linear range from 0.1 to 70 mu mol L-1 and low limit of detection with 0.03 mu mol L-1 (based on the signal to noise ration = 3) for H2O2 detection. Crown Copyright (C) 2014 Published by Elsevier B.V. All rights reserved.