Interest in CO2 solubility in brine at high pressure and high temperature has grown in the last few decades. Solubility data are especially important in petroleum geology, carbon capture and geological storage, and geothermal, reservoir engineering. Nevertheless, for,lithe CO2 + NaCl + H2O system there are fewer solubility data available in literature, particularly at high salt molality. A high-pressure experimental device was designed to perform measurements for carbon dioxide solubility in a complex aqueous solution. The apparatus was first validated from. experiment on The CO2-pure water system at 323.15 K by comparison with literature data. Thirty-six new experimental solubility data point were obtained in the pressure range between 5 and 20 MPa at three temperatures (323.15, 373.15, and 423.15 K) and at three molalities of NaCl (1, 3, and 6 moles per kilogram of water) Solubility measurements were obtained by potentiometric titration after sample trapping in a sodium hydroxide solution. The experimental solubility data generated in this work were consistent with literature data, and four original isotherms were obtained at high salinity.