Platinum nano-particles were directly fabricated through molecular dissociation process induced by tightly focused femtosecond laser pluses in hydrogen hexachloroplatinate (IV) hexahydrate (H2PtCl6 center dot 6H(2)O) aqueous solution. After irradiation, it was found that UV-visible absorption spectrum of the solution was changed and a large number of small platinum particles were synthesized. The variation of absorbance in the spectrum and the yield the particle synthesis depended on the concentration of the solution. The most effective condition for particle synthesis was 0.1 wt%. Black precipitates of platinum particles were observed in the bottom of the vessel after irradiation in some cases. The dispersibility of the particles was greatly improved by the addition of polyvinylpyrrolidone (PVP) as a dispersant, and no precipitates were found in the solution with 1.0 X 10 (2) wt% PVP. Consequently, highly monodispersed platinum nano-particles with the mean size of about 3 nm were successfully fabricated. (C) 2009 Elsevier B.V. All rights reserved.