We report an efficient method for anchoring Pt clusters (e.g., 6 nm in size) on the surfaces of N-doped multi-walled carbon nanotubes (MWNTs-CNx) using a relatively simple method consisting of a hydrothermal treatment of Na-2[PtCl6] center dot 6H(2)O and N-doped nanotubes dispersed in acetic acid. The catalytic properties of this material were evaluated finding that the conversion of cinnamaldehyde using Pt-coated MWNTs-CNx could increase up to 6 times with respect to that obtained for uncoated MWNTs-CNx and pure carbon CNTs. Therefore, we envisage this material could be either used as an efficient catalyst or as a sensor. (c) 2008 Published by Elsevier B. V.