The reduction of oxygen to water is one of the most important reactions in electrochemistry with regards to the wide range of applications in electrocatalysis, metal corrosion, and fuel cell and mostly in biosensor studies. Present study describes the use of a glassy carbon electrode modified with platinum and molybdenum oxide (Pt-MoOx) in strongly acidic solutions for electrocatalytic reduction of oxygen dissolved in buffer solution for the first time. The dispersion of Pt nanoparticles on MoOx provides larger surface area and better electrocatalytic activity for oxygen reduction and the best response toward dissolved oxygen was obtained with a mole ratio of 1: 90 Pt:Mo in deposition solution. The modified surface was then used as a biosensing platform for the monitoring of oxygen consumption due to the bio-catalytic action of glucose oxidase (GO(x)) as the model enzyme. After optimization of the operational conditions, analytical characterization and application of the glucose oxidase GO(x) biosensor to flow injection analysis mode have been successfully performed. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.