Using a static method three individual compounds in system of Pt-Cl: PtCl4, PtCl3, and PtCl2 are shown to exist. PtCl was shown not to exist. The enthalpies of formation of platinum chlorides were measured by calorimetry by reduction of the compounds with gaseous hydrogen. The recommended values for the enthalpies of formation at 298.15 K are -137.7 +/- 0.3, 194.2 +/- 1.0, and 245.6 +/- 1.9 kJ/mol for PtCl2(s), PtCl3(s) and PtCl4(s), respectively. (C) 2008 Elsevier B.V. All rights reserved.