TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Process: The reaction temperature is 20-100 (preferably 50-90)degreesC. The ratio of metals in the multimetal metal oxide particles is regulated by the ratio of salts used. The immobilized metal oxide particles are then reduced, preferably with hydrogen, hypophosphite, formate or an alcohol, especially (m)ethanol, or electrochemically.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The salt of a main group metal, preferably tin (Sn), especially a chloride SnCl2 or SnCl4, may also be used. The support may be an oxide, preferably alumina (Al2O3), titania (TiO2), silica (SiO2), cobalt oxide (Co3O4), SnO2, calcium carbonate (CaCO3), magnesia (MgO) or lanthanum oxide (La2O3); or carbon black or activated charcoal. The base is an alkali(ne earth) (hydrogen) carbonate, hydroxide or (hydrogen) phosphate, preferably of lithium (Li2CO3), sodium (Na2CO3), potassium (K2CO3), cesium (Cs2CO3) or magnesium (MgCO3).Preferred Composition: The catalysts contain oxides of not less than 3 metals, comprising Pt, Ir and other sub-group metal(s) M'. The main group metal is Sn. In particular, the catalysts contain oxides of not less than 3 metals selected from Pt, Ir, Ru, osmium (Os), W, molybdenum (Mo), palladium (Pd) and Sn. EXAMPLE - The apparatus used was cleaned to remove any traces of metal and grease present. Carbon black (400 mg) was suspended in a solution of 1.5 equivalent lithium carbonate in 3/5 of the volume of ultra-high quality water for a 10 mM batch. Platinum (Pt) (salt 0.5 mmole) in 1/5 the amount of water was dripped into the suspension, then the rest of the metal salt was added to give a 10 mM solution with respect to the total noble metal content. The suspension was kept at pH 9-10 and stirred at 60degreesC until (after 6 hours) reaction was complete, then centrifuged. The solid was washed 3 times, centrifuged and freeze dried. This gave 387.0 mg catalyst containing 13.17 wt.% Pt as dioxide, average particle diameter 1.2 +/- 0.3 nm.