The phase equilibria and saturated fluid properties of CO2 + PDMS (polydimethylsiloxane) systems were measured to investigate suitability for future hydrodynamic experiments. Two PDMS fluids graded at 100 cSt (M-w = 14 300, M-z = 22 000, D-M = 1.59) and 200 cSt (M-w = 18 400, M-z = 53 000, D-M = 4.72) were selected. Saturation pressure, and hence phase transition pressure, was determined for 1-70 wt% PDMS in CO2 at 313-353 K using the variable volume view cell method (SynVisVar). The density and dynamic viscosity were measured at saturation using the quantified volume and mass, and the converse piezoelectric effect, respectively. In agreement with the literature, the phase equilibria showed complex phase behaviour. Additionally, fluid properties deviated significantly from that of the respective pure components. It was found that both systems exhibited low solubility in CO2 (< 1% above 20 MPa), with properties in the desired ranges (similar to 900-800 kg/m(3) and similar to 0.7-7 mPa.s) for planned future hydrodynamic experiments.