Immobilization of carbon-supported Pt/Pd nanoparticles (that have been modified with ruthenium oxo species) within the tungsten oxide film containing Pt/Ru nanoparticles results in the enhancement of the catalytic properties towards electrooxidation of methyl formate in 0.5 mol dm(-3) H2SO4. The over-coating of Pt/Pd nanoparticles with cationic Ru-oxo species facilitates their attachment to tungsten oxide matrix. Because oxidation of the ester is mechanistically complex and it is expected to occur most rapidly on the formate component, the comparative measurements have been done with formic acid. In spite of modification of Pt/Pd with Ru-oxo species, the system retains high electrocatalytic activity during oxidation of formic acid. It is rationalized that not only Pt/Ru is catalytic towards oxidation of methyl formate (or products of its hydrolysis) but also oxoruthenium modified Pt/Pd is capable of promoting effectively the oxidation of formic acid or formate component of the ester. The multifunctional activity of co-deposited Pt/Ru and Pt/Pd centers is supported by good electronic and protonic conductivities of hydrated tungsten oxide matrix. (c) 2006 Elsevier B.V. All rights reserved.