The physicochemical characteristics of phase transitions of PtCl2 were investigated for the first time. The irreversible character of the transition from beta-modification to alpha-form of PtCl2 and the temperature range of process were established (570-870K). alpha-PtCl2 has one reversible transition at a temperature of 660 +/- 5K; the thermal effect of this process is +167 +/- 17J/mol. (C) 2008 Elsevier B.V. All rights reserved.