NOVELTY - Obtaining fully or partially metallic nanoparticles comprises: (a) preparing an oil-in-water (o/w) type of microemulsion comprising surfactant, an aqueous component, and an oily component that contains an organometallic precursor; and (b) adding to the microemulsion prepared in (a) a reducing agent, an oxidizing agent, or a precipitating agent.    USE - The methods are useful for obtaining fully or partially metallic nanoparticles; obtaining a deposit comprising the dispersion of (1) in a solid support; and as catalysts, catalyst support material, polishing material for glass or microelectronic components, active ingredients in sunscreens, phosphorescent or luminescent materials, biomedical vectors for diagnosis or therapy, contrast agents, or ingredients of cosmetic formulations or dermapharmaceuticals, sensors, components analysis systems, solar cells, fuel cells, fuel additives, electronic components and microelectronic components, storage systems or data transmission, optical components, magnetic components, filters, or in textile processing, components in the printing industry, components in the construction industries or mechanical components in coating products, components of vitreous materials, ceramics, plastics, natural or synthetic ingredients or components of piezoelectric mechanisms in superconductors or semiconductors (all claimed).    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are:    (1) a dispersion of wholly or partially metallic nanoparticles obtainable by the method above;    (2) a method for obtaining a deposit comprising the dispersion of (1) in a solid support;    (3) a system comprising the solid supported nanoparticles obtainable by the method of (2);    (4) a fully or partly metallic nanoparticles obtained by the method above;    (5) use of the nanoparticle dispersion of (1) or (4) as catalysts, catalyst support material, polishing material for glass or microelectronic components, active ingredients in sunscreens, phosphorescent or luminescent materials, biomedical vectors for diagnosis or therapy, contrast agents, or ingredients of cosmetic formulations or dermapharmaceuticals, sensors, components analysis systems, solar cells, fuel cells, fuel additives, electronic components and microelectronic components, storage systems or data transmission, optical components, magnetic components, filters, or in textile processing, components in the printing industry, components in the construction industries or mechanical components in coating products, components of vitreous materials, ceramics, plastics, natural or synthetic ingredients or components of piezoelectric mechanisms in superconductors or semiconductors; and    (6) use of the system of (3) as catalysts, as components in adsorbents, filters, sensors, coatings, polishing material for glass or microelectronic components, phosphorescent or luminescent materials, components analysis systems, solar cells, fuel cells, fuel additives, electronics or microelectronics, optical components in the construction industries or mechanical components in coating products, components of vitreous materials, ceramics, plastics, natural or synthetic components of piezoelectric mechanisms, treatment or textile component, components in the printing industry, superconductors or semiconductors.