The fractionation of polydimethylsiloxane (PDMS) using supercritical CO2 was studied to determine the parameters of pressure and temperature required to separate specific molecular weights. On a laboratory scale, we show that this fractionation method can quickly provide gram quantities of the polymer with a polydispersity of around 1.2 for molecular weights in excess of 200 kg/mol. This technique has obvious applications in the preparation of PDMS for surface-related uses.