We measured pressure-composition (P-x) isotherms for binary mixture of carbon dioxide (CO2) + N-vinyl-2-pyrrolidone (NVP) at temperature from 324 to 355 K and pressure up to 19.0 MPa. Phase behavior of these binary experimental data was modeled with Peng-Robinson equation of state with two adjustable parameters. And we measured cloud point pressures of carbon dioxide (CO2) + poly(vinyl pyrrolidone) (PVP) system. But PVP was not dissolved in pure CO2 up to 480 K and 290 MPa. Also we measured cloud point pressures for the ternary system of poly(vinyl pyrrolidone) (PVP) + N-vinyl-2-pyrrolidone (NVP) + carbon dioxide (CO2) using a variable volume view cell as a function of molecular weight and NVP contents at temperature up to 450 K and pressure up to 220 MPa. (C) 2003 Elsevier B.V. All rights reserved.