Polymeric biomaterials must be cleaned and sterilized prior to use in any invasive medical procedure. This must be done without damaging to the surface or bulk properties, and without compromising biocompatibility. A low temperature sterilization process based on liquid or supercritical carbon dioxide (CO2) technology has been proposed. This study investigates the effect of liquid CO2 on the mechanical properties of selected medical polymers as well as the ability of CO2-based fluids to sterilize bacteria on the surface of medical grade polymers. The tensile strength and modulus of eighteen polymers are reported. Materials were exposed to CO2 at 6.5 MPa and ambient temperature. Additionally, some polymers were processed with aqueous H2O2 mixed with CO2. CO2 uptake, swelling, and distortion were observed for the more amorphous polymers while crystalline polymers showed much less effect of CO2 exposure. Changes in tensile strength were not statistically significant for most plastics, and most indicated good tolerance to liquid CO2. The effects of CO2 treatment on water uptake, drying curves, thermal behavior and morphology of a model hydrogel poly (acrylic acid-co-acrylamide) potassium salt gel will be reported. The ability of CO2-based fluids to kill Staphylococcus aureus will also be reported.