A novel method for preparing monosized ultrafine particles of precious metals utilizing an emulsion-type liquid membrane technique has been developed, and various factors affecting the formation of these precious metal powders have been studied. Precious metal powders are readily formed at ambient temperature by mixing water-in-oil (W/O) emulsion, which consists of an internal aqueous phase containing reductant and an organic phase containing both extractant and surfactant, with an external aqueous solution containing precious metal salt. Precious metal powders can also be formed by contacting emulsion, containing precious metal salts in an internal aqueous phase, with an external aqueous phase, containing reductant. Particle size, size distribution, and morphology can be controlled, to some extent, by proper selection of the extraction and reducing conditions. Particulates formed under conditions of fast reduction are usually smaller in size.