NOVELTY - A metal-loaded mixed-metal oxide catalyst for facilitating a water gas shift reaction comprises a noble metal on a mixed metal oxide. The mixed metal oxide comprises a homogeneous, nanocrystalline, mixed metal oxide of cerium and other metal constituent(s) from zirconium, hafnium, niobium, tantalum, lanthanum, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, molybdenum, tungsten, rhenium, rhodium, antimony, bismuth, titanium, vanadium, manganese, cobalt, copper, gallium, calcium, strontium or barium.    USE - For facilitating a water gas shift reaction in fuel processing systems, e.g. fuel cells.    ADVANTAGE - The metal-loaded mixed-metal oxide catalyst exhibits fractal morphology, thus leading to a minimization in internal mass transfer resistance. The catalyst has a relatively high surface area per unit of weight, relatively small crystallite diameters, and pore diameters of the crystallites in the aggregate that normally exceed the crystallite diameters. The catalyst has an aggregated crystallite morphology that is thermally robust, and that optimizes the available surface area per unit volume, mass transfer characteristics, and the reactivity of that surface area. The catalyst can be formed by an efficient and effective process. The catalyst is highly effective and increases catalyst efficiency by maximizing the amount of effective surface area within a given reactor volume. By increasing the efficiency of the catalyst in the reaction, it is possible then to either increase the reaction flow for a given reactor volume or to decrease the reactor volume for a given reaction flow, or a combination of the two.    DETAILED DESCRIPTION - A metal-loaded mixed-metal oxide catalyst for facilitating a water gas shift reaction comprises a noble metal on a mixed metal oxide. The mixed metal oxide comprises a homogeneous, nanocrystalline, mixed metal oxide of cerium and other metal constituent(s) from zirconium, hafnium, niobium, tantalum, lanthanum, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, molybdenum, tungsten, rhenium, rhodium, antimony, bismuth, titanium, vanadium, manganese, cobalt, copper, gallium, calcium, strontium or barium. The mixed metal oxide has a surface area of greater than or equal to 150 m2/g, an average crystallite size of less than 4 nm and agglomerated to form a skeletal structure with pores, and average pore diameters of greater than 4 nm and normally of greater than the average crystallite size. The surface are of the skeletal structure per volume of the material of the structure is greater than 320 m2/cm3.    An INDEPENDENT CLAIM is included for the preparation of the catalyst, comprising:    (A) contacting the mixed metal oxide with a solution containing an acid from amino acids, hydroxy dicarboxylic acids, hydroxy polycarboxylic acids, or keto polycarboxylic acids to treat the surface of the mixed metal oxide; and    (B) loading the surface-treated, mixed metal oxide with the noble metal by contacting the surface-treated mixed metal oxide with a solution containing the noble metal.