The excess enthalpies H-E of CO2 + olive oil mixtures were measured under the conditions of temperature and pressure typically used in supercritical fluid extraction by means of an isothermal flow calorimeter. Values of H-E at 35 degrees C and 17 MPa are moderately endothermic. Values of H-E at 35 degrees C and 15 MPa are moderately endothermic in the olive oil-rich region and exothermic in the carbon dioxide-rich region. Values of H-E at 35 degrees C and 9 MPa and at 80 degrees C and 9, 15 and 17 MPa are considerably exothermic. The H-E versus composition plots show trends corresponding to a two-phase region. The changes observed in the excess enthalpy with temperature and pressure are discussed in terms of densities and critical constants of carbon dioxide, triolein and olive oil and liquid-vapor equilibrium data for CO2 + triolein, CO2 + oleic acid + triolein and CO2 + rapeseed oil.