A simple, efficient and scalable approach is developed for synthesis of Vulcan XC-72(carbon)-supported Pt nanoparticles (NPs) that combines homogeneous deposition (HD) of Pt complex species through reaction with OH- ions generated by in situ hydrolysis of urea and subsequent reduction by reducing species generated from radiolysis of water by gamma-rays. This method not only avoids addition of any commonly used reducing agent, but also offers more uniform homogeneous dispersion of Pt NPs with much smaller particle size. Thus, when used as a cathode catalyst for proton exchange membrane fuel cell, the synthesized carbon-supported Pt NPs demonstrate excellent oxygen reduction electro catalytic activity, higher Pt utilization efficiency, and considerably improved fuel cell polarization performance compared to those of Pt catalysts prepared with other synthesis strategies such as conventional NaBH4 reduction and HD-ethylene glycol method as well as commercial Pt catalyst. The combined HD-gamma-irradiation strategy is found to be simple, reproducible and efficient with mild synthesis condition and in particular, holds great promises for large scale production of highly efficient Pt-based catalysts for fuel cells. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.