The reaction of Pt-2(dba)(3) (dba = bis-dibenzylidene acetone) dispersed in room temperature 1-n-butyl-3-methylimiclazolium (BMI) hexafluorophosphate ionic liquid with molecular hydrogen (4 atm) at 75 degreesC leads to stable and isolable nanometric Pt(0) particles. The X-ray diffraction analysis (XRD) of the material indicated that it is constituted of Pt(0). Transmission electron microscopy (TEM) analysis of the particles dispersed in the ionic liquid shows the formation of [Pt(0)](n) nanoparticles of 2.0-2.5 nm in diameter. A detailed examination of the nanoparticles imbibed in the ionic liquid and their environment shows an interaction of the BMI.PF6 ionic liquid with the Pt(0) nanoparticles. The isolated [Pt(0)](n) nanoparticles can be redispersed in the ionic liquid or in acetone or used in solventless conditions for liquid-liquid biphasic, homogeneous, or heterogeneous hydrogenation of alkenes and arenes under mild reaction conditions (75 degreesC and 4 atm). The recovered platinum nanoparticles can be reused as a solid or redispersed in the ionic liquid several times without any significant loss in catalytic activity.