A novel low-temperature plasma method, using Pt acetylacetonate as a precursor, was used for the first time to produce Pt/carbon black catalysts for polymer electrolyte membrane fuel cells. Catalysts were prepared under various plasma conditions and characterized by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. Pt nanoparticles with an average diameter of around 3 nm, which are mainly metallic and quite homogeneously distributed with a Pt loading up to 40 wt%, were successfully formed on carbon black by a 100W-oxygen plasma treatment. During the plasma treatment, the precursor is thermally decomposed, and some oxidized carbon sites or defects appear at the surface of the carbon black due to interactions with the plasma; these oxidized carbon sites or surface defects probably act as anchoring sites for the nucleation of Pt nanoparticles. The decomposition of the precursor mainly depends on the plasma power whereas the formation of the anchoring sites depends on the stirring of the reactants and on the nature of the plasma gas. (C) 2013 Elsevier B.V. All rights reserved.