Equipment to measure the solubility of solutes in supercritical fluids (SCFs) was constructed. The solubility of the non-ionic surfactant tetraethylene glycol n-laurel ether (C12E4) in supercritical CO2 (SC CO2) with and without n-pentanol was determined at 313.5 and 323.15 K in the pressure range from 8 to 20 MPa. The effect of pressure, temperature, n-pentanol concentration, and apparent density Of CO2 (gram Of CO2 per milliliter of fluid) on the solubility Of C12E4 were systematically studied. The solubility Of C12E4 increases with increasing pressure or apparent density Of CO2. The addition of n-pentanol can enhance the solubility Of C12E4 Significantly.