In this paper, the ability of quartz crystal microbalance (QCM) was considered about in situ measurement in high pressure fluid. Solubility and adsorption of high pressure carbon dioxide (CO2) to polystyrene (PS) were measured using a QCM as a detector at pressures up to 17 MPa at 313. 2 K. The solubility and surface adsorption of CO2 increased almost linearly against activity of CO2. And it was found that the present method could be applied to higher pressure range than any other methods. The activity plot of solubility at various temperatures fell into one universal line. This may be very important because it suggests the possibility of obtaining the solubility at any temperature from only one measurement.
