Abstract Palladium metal particles with an average diameter of ca. 5 nm were homogeneously dispersed inside carbon nanotubes. Such nanostructured material was an extremely active and selective catalyst for the hydrogenation of the C=C bond of cinnamaldehyde. The high external surface area of the carbon nanotubes could explain the high reactivity of the catalyst despite its relatively low specific surface area, i.e. 20 m2.g-1. On the other hand, the high selectivity towards the C=C bond hydrogenation was attributed to the absence of a microporous network and of residual acidic sites in the carbon nanotube catalyst as compared to a commercial activated charcoal.