An apparatus for extracting organic compounds from plant materials using subcritical or supercritical carbon dioxide is described. The apparatus has a sealable pressure chamber into which carbon dioxide dry ice and the plant materials are inserted, the pressure chamber, once sealed, self-pressurizing as the container and contents are warmed to a chosen temperature, converting the solid CO2 to liquid, or to a super-critical fluid as the temperature and pressure are raised above the Critical Point. The chamber can be rotated when subcritical CO2 liquid is employed to improve mixing between the liquid and the plant material. After a suitable extraction time, the carbon dioxide solvent containing the extracted material is directed into a separator such that the carbon dioxide and extracted material can be effectively separated, thereby avoiding significant quantities of viscous and waxy extracted materials remaining in the chamber and valves after the carbon dioxide solvent is warmed and allowed to exit the chamber.