TECHNOLOGY FOCUS - POLYMERS - Preferred Polymer: The polymetallic precursor is a non-cluster polymetallic precursor. It is Pt(triphenylphosphine) (Cl)-(mu-Cl2)Ru(Cl)(trihapto:trihapto-2,7-dimethyloctadienediyl), (Pt3(mu-bis(diphenylphosphino)methane)3(Ru)(pentahapto-(cyclopentadienyl))(hexafluorophosphate), (Ru(mu-2,3-bis(2-pyridyl)quinoxaline)PtCl2)3)(tetrafluoroborate)2, (Pt3(mu-bis(diphenylphosphino)methane)3(mu-Mo)(pentahapto-cyclopentadienyl)(CO))(hexafluorophosphate), (Pt3(bis(diphenylphosphino)methane)3(mu-Mo)(pentahapto-cyclopentadienyl)(CO))(tetraphenylborate), (Pt3(mu-bis(diphenylphosphino)methane3(mu3-Hg-Ru(pentahapto-cyclopentadienyl)(CO)2)2)(hexafluorophosphate)2, (Ru(2,2'-bipyridine)2(mu-bipyrimidine)PtCl2)(tetrafluoroborate)2, Pt(dihaptoethylene)(Cl)(mu-Cl)2Ru(Cl)(trihapto:trihapto-2,7-dimethyloctadienediyl), or (Pt3(mu-W)(pentahapto-cyclopentadienyl)(CO)(mu-bis(diphenylphosphino) -methane)3)(hexafluorophosphate).Preferred Process: Heating of the contacted support involves heating in the presence of hydrogen-containing gas reducing agent. The support is heated to a temperature greater than the degradation temperature of the ligand. The polymetallic nanoparticles are annealed by holding the support at that temperature to form a crystalline structure. The method further includes heating the contacted support in the presence of an oxidizing agent, contacting the support with a solution or suspension of the polymetallic precursor a second time, heating the support the second time in the presence of an oxidizing agent, and repeating the steps. Heating of the support is controlled at 10-20 degrees C/minute.Preferred Dimension: The nanoparticles have a mean diameter of at most 5 nm.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: The polymetallic precursor comprises a trigonal-bipyramidal Pt3Hg2. At least one of the metals is a noble metal.Preferred Composition: The ratio of the first metal to the second is at least 1. The support comprises particulate carbon.Preferred Property: The support is electrically conductive. The particulate carbon has a mean particle diameter less than 30 nm and a specific surface area of at least 250 m2/g. Preferred Definitions:    X = bridging ligand, preferably mercury; and    M = platinum.    EXAMPLE - Binuclear non-cluster precursor complex (Ru(mu-bipyrimidine)(2,2'-bipyridine)2PtCl2)(hexafluorophosphate)2 (0.29 g) was dissolved in acetonitrile (50 ml). The solution was stirred with a carbon support (0.31 g). The resulting precursor/carbon composite was placed into a tube furnace and was treated thermally under 25-280 degrees C under air, 280-650 degrees C under getter gas, and afterwards cooled. A second deposition of the precursor complex (0.27 g) was carried using a solution in acetonitrile and solvent evaporation. The precursor/carbon composite was again heated under the same conditions and then thermally annealed at 650 degrees C under nitrogen for 60 minutes. The sample was cooled afterwards. It demonstrated good fuel cell properties in a DMFC test cell.