On the basis of the emulsion polymerization process poly(indole- co -thiophene) supported Fe 3O4 NPs nanocom- posite was synthesized at room temperature. The structure and chemical composition of the nanocomposite were described by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. Due to its uniform pore structure, high surface areas and good biocompatibility, the chains of PIT@Fe3O4 nano- composite are able to provide a suitable matrix for immobilization of biomolecule. Glassy carbon electrode mod- i fi ed with PIT@Fe 3O 4 nanocomposite was used as support for immobilizatio n of hemoglobin (Hb) protein to fabricate an electrochemical biosensor. The electrochemical studies for the biosensor shows that it has excellent property for direct bioelectrocatalytic performances of hemoglobin, and could sense hydrogen peroxide at a low detection limit of 0.54 μM and a linear range up to 350μM. The developed biosensor confirmed an excellent per- formance in the detection of hydrogen peroxide in environmental and food samples.