This study presents an equation of state for mixtures of HFC-32, HFC-125, and HFC-134a based on available PVTx, VLE, heat capacity and speed of sound measurements. The equation of state is valid for VLE and superheated gaseous and compressed liquid phases from 200 to 470 K and pressures up to 20 MPa. The equation is also valid for ternary mixtures of HFC-32, HFC-125, and HFC-134a. (C) 1998 Elsevier Science B.V. All rights reserved.