Phase equilibrium data have been measured for the ternary system hyperbranched polyglycerol + methanol + carbon dioxide at temperatures of 313-450 K and pressures up to 13.5 MPa. Phase changes were determined according to a synthetic method using the Cailletet setup. At elevated temperatures the system shows a liquid-liquid-vapor region with lower solution temperatures. Besides the vapor-liquid and liquid-liquid equilibria, the vapor-liquid to vapor-liquid-liquid and vapor-liquid-liquid to liquid-liquid phase boundaries are reported at different polymer molar masses and can serve as test sets for thermodynamic models. A distinct influence of the polymer molar mass on the vapor-liquid equilibrium can be noticed and indicates the existence of structural effects due to the polymer branching. Modeling the systems with the PCP-SAFT equation of state confirms these findings. (C) 2010 Elsevier B.V. All rights reserved.