NOVELTY - Preparation (P1) of a composition of cobalt (Co) and palladium (Pd) supported on an inert material involves reducing a cobalt compound and depositing the Co(0) metallic nanoparticle obtained on the surface of a particle consisting of an inert material selected from aluminum oxide, titanium oxide, zirconium oxide, silicon oxide, cerium oxide and mixed cerium and zirconium oxides; depositing Pd(0) on the Co(0) nanoparticles and inert material composition; and conditioning the composition of cobalt and palladium supported on an inert material.    USE - For preparation of composition of cobalt and palladium supported on an inert material used as catalyst for an oxy-reduction reaction selected from Water Gas Shift Reaction (WGSR), for preferential or non-preferential oxidation of carbon monoxide to carbon dioxide and oxy-reduction reaction occurring in fuel cells, preferential oxidation (PROX) of carbon monoxide to carbon dioxide with controlled quantities of oxygen in an atmosphere rich in hydrogen; and for preparation of a catalytic device (claimed).    ADVANTAGE - The process provides stable and innovative catalyst at a reduced cost. The resulting catalyst has a higher degree of efficiency and duration.    DETAILED DESCRIPTION - Preparation (P1) of a composition of cobalt and palladium supported on an inert material involves reducing a cobalt compound and depositing the Co(0) metallic nanoparticle obtained on the surface of a particle consisting of an inert material selected from aluminum oxide, titanium oxide, zirconium oxide, silicon oxide, cerium oxide and mixed cerium and zirconium oxides; depositing Pd(0) on the Co(0) nanoparticles and inert material composition; and conditioning the composition of cobalt and palladium supported on an inert material, where the two first steps of Co(0) and Pd(0) nanoparticle deposition are performed under argon flux and the third step of conditioning is performed under argon, hydrogen and argon fluxes on the dry powder consisting of the composition of Pd(0):Co(0) supported on an inert material obtained after deposition of Pd(0) nanoparticles. INDEPENDENT CLAIMS are included for following:    (1) a composition of Pd:Co bimetallic nanoparticles supported on an inert material obtained by the method (P1); and    (2) a catalytic device comprising the composition Pd:Co bimetallic nanoparticles supported on an inert material.