TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Particle: The nanocomposite particle additionally comprises at least one region of a second noble metal on the surface, where the second noble metal is different to the first noble metal. The nanocomposite particles of the nanocomposite material have a mean diameter of 3-15 nm. Preferred Components: The first noble metal and, if present, the second noble metal, are selected from gold, platinum, palladium, rhodium, osmium, silver, ruthenium and iridium. The silver salt is silver sulfide. The noble metal on the surface of nanocomposite particles of the nanocomposite material is platinum. Preferred Process: The process (P1) additionally involves combining the dispersion with further reducing agent and a compound or complex of the second noble metal, and maintaining the resulting mixture at an elevated temperature for sufficient time to form at least one region of the second noble metal on the surface of the nanoparticles, where the second noble metal is different to the first noble metal, thus forming an aqueous dispersion of the nanocomposite material in which the nanoparticles comprise at least one region of the first noble metal and at least one region of the second noble metal on its surface. The process (P1) involves preparing the nanoparticles by a combining an aqueous solution of a water soluble silver salt and a stabilizing agent with an aqueous solution of a water soluble salt comprising a counterion capable of forming an insoluble salt with silver ions, so as to form the nanoparticles in the form of an aqueous dispersion of the silver salt of the counterion. The process (P1) for making the nanocomposite material involves: combining a heated aqueous mixture comprising nanoparticles and the reducing agent with at least two compounds or complexes of different noble metals or with a mixed metal compound or complex comprising at least two different noble metals in the same compound or complex, where the nanoparticles each having a surface comprising a silver salt; and maintaining the resulting reaction mixture at an elevated temperature for sufficient time to form either at least one region of each noble metal or else at least one region of a mixture of the noble metals on the surface of the nanoparticles, thus forming an aqueous dispersion of the nanocomposite material. The process (P1) additionally involves: adding to the aqueous dispersion of the nanocomposite material a solution of an amine in a water soluble organic solvent, and agitating the resulting mixture with a second solvent which forms a two phase system with the mixture, so as to transfer the nanocomposite material to the second solvent and form a dispersion of the nanocomposite material in the second solvent.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The reducing agent comprises citric acid and/or citrate. The stabilizing agent is bis(para-sulfonatophenyl)phenylphosphane dihydrate dipotassium salt. The solvent (s1) is an aromatic hydrocarbon solvent. EXAMPLE - A silver sulfide (Ag2S) hydrosol (60 ml) was refluxed at 110 degrees C for 3 minutes in a flask, followed by the addition of aqueous sodium citrate solution (100 mM, 3 ml). The mixture was refluxed one more minute at 110 degrees C and then 50 mM aqueous K2PtCl4 solution (1.2 ml) was added swiftly. The reaction mixture was continuously refluxed for 120 minutes at 110 degrees C to form the hydrosol of Ag2S-Pt nanocomposites. The Pt/Ag2S precursor molar ratio was controlled by mixing different volumes of aqueous K2PtCl4 solution and Ag2S hydrosol.