Electrochemical behavior of bis(acetylacetonato)platinum(II) (Pt(acac)2) was investigated in an amide-type ionic liquid, trimethylhexylammonium bis(trifluoromethylsulfonyl)amide (TMHATFSA), at various temperatures. Ultraviolet visible spectroscopy revealed the existence of Pt(acac)(2) having square planar geometry in TMHATFSA. The electrochemical reduction of Pt(acac)(2) to Pt(0) was considered to occur with formation of some intermediate species of Pt by cyclic voltammetry. Potentiostatic cathodic reduction on a glassy carbon electrode in TMHATFSA containing Pt(acac)(2) at -1.7 Vat 130 degrees C resulted in deposition of metallic Pt, which was confirmed by scanning electron microscopy and energy dispersive X-ray spectroscopy. In addition, formation of Pt nanoparticles dispersed in the ionic liquid after potentiostatic cathodic reduction was confirmed by transmission electron microscopy and electron diffraction. The sizes of the Pt nanoparticles were found to depend on the reduction potential. (C) 2016 The Electrochemical Society. All rights reserved.