High pressure experimental data are presented on the phase behavior of 2,2-dimethyl-1,3-propanediol in carbon dioxide. Pressure-composition (P-x) isotherms were measured from 352.3 K to 403.2 K. The single phase of the mixture greatly reduces with decreasing temperature due to the hydrogen bonding of 2,2-dimethyl-1,3-propanediol. The P-x isotherms at 352.3 K and 353.3 K exhibited an open loop whereas the P-x isotherms at the higher temperatures did a closed loop. The 2,2-dimethyl-1,3-propanediol + CO2 phase behavior was modeled with Peng-Robinson equation of state with two mixture parameters. A reasonable fit of the high temperature isotherms is obtained if k(ij) is allowed to increase with decreasing temperature. The fit of the data becomes inaccurate with deceasing temperature due to the hydrogen bonding between 2,2-dimethyl-1,3-propanediol molecules.