We report a durable and active electrocatalyst, Pt/carbon nitride (CNx) modified silicon dioxide (SiO2) composite (donated as CNx/SiO2), for oxygen reduction reaction (ORR). CNx/SiO2 composite is synthesized by calcination of polypyrrole coated SiO2 (PPy/SiO2) at 800 degrees C. The structure and composition are assessed using Fourier transform infra-red spectroscopy, X-ray diffraction, transmission electron microscope and energy dispersive spectroscopy. Voltammetry is used to study the activities of Pt immobilized on Vulcan XC-72R and CNx/SiO2, respectively. The electrochemical data indicate that Pt supported on CNx/SiO2 possesses higher electrocatalytic activity and durability for ORR compared with those of Vulcan XC-72R. All these demonstrate that CNx/SiO2 is a promising ORR electrocatalyst support for low temperature fuel cells. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.