Solubility data of carbon dioxide (CO2) (1) in methanol (2), 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([omim]+[Tf2N]-) (3), and their mixtures (w3=0.2, 0.5, and 0.8) at temperatures 313.2 and 333.2 K and pressures up to 7.0 MPa were measured by a high-pressure view-cell technique. The solubility of CO2 in methanol (w3=0), ([omim]+[Tf2N]-) (w3=1.0) and their mixtures follows the order of (w3=0)<(w3=0.2)<(w3=0.5)<(w3=0.8)<(w3=1.0) at the same temperature and pressure, while the magnitude of Henry’s constants follows the reverse order at a given temperature, which is consistent with the COSMO-RS (conductor-like screening for real solvents) calculation. The solubility data of CO2 in methanol and [omim]+[Tf2N]- are correlated with the Peng-Robinson equation of state, and the solubility of CO2 in the mixtures of methanol and [omim]+[Tf2N]- can be well predicted based on the mole fraction average of methanol and [omim]+[Tf2N]- over the solubility of CO2 in pure methanol and [omim]+[Tf2N]-. The mixtures of methanol and [omim]+[Tf2N]- may be used as physical solvents for capturing CO2 with high partial pressures since they combine the advantages of organic solvents and ionic liquids. Solubility data of carbon dioxide (1) in methanol (2) of 1-octyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide ([omim] + [Tf2N] , 0.5, and 0.8) at temperatures 313.2 and 333.2 K and pressures up to 7.0 MPa were measured by a high-pressure view-cell technique. The solubility of CO2 in methanol (w3 = 0), ([omim] + [Tf2N] - (w3 = 1.0) and their mixtures follows the order of (w3 = 0)