A facile ion implantation method was developed to prepare a novel Pt nanoparticles loaded ITO (PtNPs/ITO) electrode. The resulting nanoparticles were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and electrochemical methods. From the result of electrochemical oxidation of nitrite, we observed that the PtNPs/ITO electrode exhibited excellent electrocatalytic activity, which might be useful in nitrite sensor. The oxidation current of nitrite was linear to its concentration in the range of 5-800 mu M and the detection limit (S/N=3) was down to 0.4 mu M. Upon immobilization of the surface of PtNPs/ITO with cytochrome c, Cyt c/PtNPs/ITO for H2O2 biosensor was developed. The characteristics of the biosensor were studied by UV-vis absorption spectra and electrochemical methods. The results revealed that the modified electrode could enhance electron transfer of Cyt c and retain electrochemical activity, good stability and reproducibility. The immobilized Cyt c exhibited a rapid response to H2O2, low detection limit of 0.1 mu M and high sensitivity of 37.20 mu A mM(-1). Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.