FOR THE CATALYTIC STEAM REFORMING OF HYDROCARBONS, A NOVEL CATALYST COMPOSITION SUBSTANTIALLY FREE OF ALKALI METAL OXIDE AND (A) A CARRIER COMPRISING 70-100% UNCOMBINED MAGNESIA, 0.30% OF A SPINELLE. THE LATTER BEING A PRODUCT OF MAGNESIA COMBINED WITH AN OXIDE OF TRIVALENT METAL, AND 0-15% OF SIO2 IN THE FORM OF AN ALUMINUM SILICATE, AND (B) A CATALYTICALLY ACTIVE METAL SELECTED FROM THE GROUP CONSISTING OF COBALT, NICKEL AND MIXTURES THEREOF. AT LEAST A PORTION OF THE ACTIVE METAL IS IN THE FORM OF A COATING ON THE INTERNAL POROUS SURFACES OF THE CARRIER. THIS CATALYST HAS A LONG LIFE AND IN PARTICULAR DOES NOT LEAD TO CARBON BLACK FORMATION.