This work aims at enhancing Pt utilization in electrocatalysts by covering of preformed silica nanoparticles. Pt/C electrocatalysts were prepared by reductive deposition of Pt by citrate at moderate temperatures on silica nanoparticles with varying atomic silica to Pt ratios (1.71 and 3.3:1) to study the effects of silica to Pt ratio. Considerable voiclages were created by inter-situated 10-20 nrn silica nanoparticles between support carbon particulates to facilitate mass transfer of reactants and products. This particular method of catalyst preparation increases the Pt metal utilization, and generates a large amount of accessible voidage in the interpenetrating particle network of carbon and silica to support the facile transport of reactants and products. Electrochemical hydrogen adsorption/desorption has shown an increase in electrochemically active surface area by this approach. Methanol electro-oxidation was used as a test reaction to evaluate the catalytic activity. It was found that the Pt catalyst modified with silica at silica:Pt=1.7:1 atomic ratio was more active than a catalyst prepared when silica to Pt ratio increased to 3.3: 1. (c) 2008 Elsevier B.V. All rights reserved.