Fe3O4/PPy/Ag nanocomposites with core/shell/shell structure were prepared and used for fabricating nonenzymatic H2O2 sensor. The nanocomposites were prepared with a three-step process, and proved by characterizations such as transmission electron microscopic, X-ray diffraction and X-ray photoelectron spectroscopy. The electrochemical investigation revealed that the composites had excellent catalytic property toward H2O2. The sensor could detect H2O2 with a wide linear range from 5 mu M to 11.5 mM, and a low detection limit of 1.7 mu M. Additionally, the sensor exhibited long-term stability, good reproducibility and anti-interference. (C) 2015 Elsevier B.V. All rights reserved.