Sterilization using supercritical carbon dioxide has been proven to be efficient for decades now. The aim of this work was to implement a process of sterilization adapted to thermosensitive polymeric materials and highlight the lowest conditions of pressure and temperature which would enable a bacterial reduction higher than 6-log. Inactivation experiments were performed on spores of Bacillus subtilis over a pressure range lying from 60 to 200 bar, and a temperature varying from 35° to 60°C, with and without additive. Preliminary experiments allowed us to determine a restricted experimental domain used for the design of the experiments, investigating the influence of pressure, temperature, process duration, and additive content on bacterial reduction. It was shown that sterilization conducted at 110 bar, 40 °C, for 20 min with 200 ppm of H2O2, leading to a bacterial reduction of 8.73-log, may be considered as optimal for IMD sterilization.