A static equilibrium apparatus was built for determining solid solubility in supercritical fluid. Solubilities of polystyrene in supercritical propane were determined by the static equilibrium method at temperature from 383.15 K to 408.15 K and pressure from 10.0 MPa to 35.0 MPa. The effects of temperature and pressure on the solubility of polystyrene were investigated. The results showed that the solubility of polystyrene in supercritical propane increased with the increase of temperature and pressure. It was also shown that retrograde area could not exist within the temperature and pressure range. Furthermore

the solubility data of polystyrene in supercritical propane were correlated with the fairly good accuracy by a solution model presented in literature. The average absolute relative deviation (AARD) was 4.93%.