TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preparation (claimed): Preparation of (C1) involves:(i) dissolving an Ni-salt (a) in a solvent to obtain a solvent solution of (a);(ii) adding an Mg-containing compound (b) to form a slurry with the solvent solution of (a);(iii) driving off an amount of solvent to form a paste consisting of (a), (b) and solvent;(iv) drying the paste to form a powder consisting of (a) and (b);(v) calcining the powder at 350-1000 degrees C to decompose (a), but without the vaporization of Ni;(vi) grinding the calcined powder to a finely divided state; and(vii) subjecting the finely divided powder to a reducing environment at 500-1200 degrees C.Preferred Composition: The molar ratio of Ni to Mg is 1.8:1-2.8:1, preferably 2.0:1-2.8:1. The percentage of Ni in the metallic state is from 55-80%, preferably 65-75%. The molar ratio of Ni to Cu is 9:1-7:3, preferably 4:1. The percentage of Ni and Cu in the metallic state is 50-90%, preferably 70-85%.Preferred Components: The solvent is water. The nickel salt (a) is selected from Ni nitrate, Ni chloride or Ni sulfate. The magnesium containing compound (b) is selected from Mg oxide, Mg hydroxide, Mg nitrate, Mg sulfate or Mg chloride (preferably Mg oxide).    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The nickel salt (a) is selected from Ni acetate or Ni carbonate (preferably Ni nitrate). The magnesium containing compound (b) is selected from Mg carbonate or Mg acetate. EXAMPLE - The decomposition of methane was performed using a catalyst composition of NixMgyO catalyst (where x and y is the molar amount of Ni and Mg respectively, and the ratio x:y is 2.4:1) and the yields of hydrogen and solid carbon products were determined. The decomposition reaction was carried out in a quartz flow reactor. The powdered catalyst sample (50 g) was placed in a ceramic boat at the center of the reactor in a furnace and the system was flushed with argon for 0.5 hours. The catalyst powder was initially calcined at 500 degrees C in air and reduced at 850 degrees C in 10% H2/argon at 850 degrees C. The system was again flushed with argon, methane was introduced at a rate of 60 ml/minute into the reactor and allowed to react with the catalyst at 550 degrees C under atmospheric pressure conditions. The reaction was carried out to the point at which complete deactivation of the catalyst occurred. The progress of the reaction was followed by a function of time by sampling the inlet and outlet gas streams at regular intervals and analyzing the reactants and products. The H2 yield (L-H2/g-Cat) and the solid carbon yield (g-C/g-Cat) were found to be: 616 and 165, respectively.