Experimental cloud-point data to 220 degrees C and 2660 bar are reported for binary and ternary mixtures of poly(octyl acrylate) [P(OA)] +CO2 +octyl acrylate (OA), poly(octyl metbacrylate) [P(OMA)] + CO2 + octyl methacrylate (OMA), and P(OA) + supercritical solvents systems. The cloud-point curves for the P(OA) + CO2 + OA (or dimethyl ether (DME)) system changes the pressure-temperature (P-7) curve from upper critical solution temperature (UCST) region to lower critical solution temperature (LCST) region as the OA (or DME) concentration increases. The P(OA) + C-4 hydrocarbons cloud-point curves are similar to 150 bar lower than the P(OA) + C-3 hydrocarbons curves at fixed temperature. The phase behavior for the system P(OMA) + CO2 + OMA are measured in changes of the P-T slope, and with cosolvent concentrations of 0-42.4 wt.%. High pressures phase behavior data are measured for the CO2 + OA and CO2 + OMA systems at the temperature range from 40 to 120 degrees C and pressures up to similar to 208 bar. Both system exhibit type-I phase behavior with a continuous mixture-critical curve and both are adequately modeled with the Peng-Robinson equation of state. (C) 2006 Elsevier B.V. All rights reserved.