The present invention is based on the discovery of particularly interesting performances of supported metallic catalysts containing at least one metal of group VIII deposited on a carrier composed of a mixed spinel of the formula M,M'1-x Al2 O4, M being a bivalent metal of group VIII specifically chosen from metals such as iron, nickel and cobalt and M' being a bivalent metal of group 2a, 7b, 1b o