A novel technique was explored for the preparation of a Pt-C catalyst-working electrode film of low particle size (15 nm), which can be electrochemically promoted at low temperatures. A Pt/C commercial catalyst powder was used as a precursor of the catalyst film on the solid electrolyte cell. The removal at low temperatures of the initial C matrix on the sprayed catalyst ink, allows to have a Pt/C catalyst-working electrode layer with a suitable morphology, thermal stability and electronic conductivity as supported by several characterization techniques (TGA, XRD, SEM, C analysis and electrical resistance measurements). The Pt-C catalyst film was successfully electrochemically promoted (by potassium ions) for the simultaneous CO and C3H6 oxidation reactions under a gas atmosphere which simulates an exhaust stream coming from a gasoline engine. The obtained higher catalytic activity, in comparison with previous studies and the occurrence of an oscillatory phenomenon, which can be electrochemically modified, are interesting results for this new Pt-C based electrochemical catalyst. (C) 2009 Elsevier B.V. All rights reserved.