In this paper phase-equilibrium measurements for the poly(methyl methacrylate)/methyl methacrylate/carbon dioxide ternary system are presented. The experimental data were obtained by cloud-point measurements and by applying a novel spectroscopic device. The influence of temperature, pressure and the polymer molecular weight on the phase behavior of the ternary system was investigated. Modeling with the PC-SAFT equation of state shows a very good agreement with the experimental data. (C) 2008 Elsevier B.V. All rights reserved.