Ionic liquids (ILs) have attracted much research interest because their unique physical and chemical properties, including negligible vapor pressure, thermal and air stability, low flammability. In this work, we show the synthesis of noble metals, such as gold and platinum, using1-butyl-3-methylimidazolium bis(triflylmethyl-sulfonyl)imide ([BMIM][Tf2N]) ionic liquid without the conventional capping agents. The resultant nanoparticles can be stabilized in the IL phase. Noticeably, these nanoparticles can be stabilized in either organic or aqueous phase using different ligand chemistry, providing great flexibility for surface modifications and resulting in dramatic narrowing in size distribution. The catalytic activity of Pt in hydrogenation of cyclohexene was studied.