Two types of experimental apparatus were designed to measure bubble point pressure for supercritical carbon dioxide (CO2) + lubricating oil. One was based on a synthetic method, and the other was on a recirculating method. An oscillation U-tube densimeter was also equipped with the recirculating type apparatus to measure the liquid density. Ensuring the reliability of the experimental data, bubble point pressure was measured for CO2 + decane (C10H22) at 344.3 K. The experimental data of the bubble point pressure and the liquid density were agreed well with the literature. Lubricating oil employed was polyalkylene glycol type one for refrigerators, commercially named PAG-1. The bubble point pressure and the liquid density were measured for CO2 + PAG-1 at 344.3 K. The experimental data were correlated with Peng-Robinson (PR) equation of state. (C) 2004 Elsevier B.V. All rights reserved.