The invention relates to novel nanoparticles comprising a metal core containing at least one platinoid or an alloy of a platinoid, a first organic coating formed from molecules attached to the surface of the metal core, and a second organic coating formed from molecules different from the molecules forming the first organic coating, and which are grafted onto molecules of the first organic coating. The invention also relates to the use of the nanoparticles as catalysts. The fields of application include devices for producing electrical energy, in particular in fuel cells, devices for detecting or assaying one or more chemical or biological species, in particular in sensors or multisensors, etc.