Abstract: The invention relates to the production of a material comprising a mixture of noble metal nanoparticles and rare-earth oxide nanoparticles. The process comprises the following successive steps: a) production of a metal alloy comprising at least one noble metal chosen from the group comprising the elements Ru, Rh, Ir, Ag, Au, Pd, Pt, Ni and Cu and at least one rare earth chosen from the group comprising the elements La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y and Sc, said alloy containing a crystalline phase the rare earth content of which is greater than 10 at % and the noble metal content of which is between 25 and 75 at %; and b) oxidation, in an oxidizing atmosphere, of the metal alloy obtained during step a). The subject of the invention is also a composite comprising a mixture of noble metal nanoparticles and rare-earth oxide nanoparticles and to the use of such a composite, in particular for catalysis.