Silicone-functional analogs to conventional surfactants have been synthesized, and their phase behavior in carbon dioxide explored at 65 degrees C and room temperature. In agreement with work by other researchers, we have observed that these silicone amphiphiles exhibited UCST type behavior in CO2, such that miscibility pressures tend to decrease as the temperature increases. Phase behavior is sensitive to the number and type of the CO2-phobic groups, moreso than to the molecular wt. of the silicons component. (C) 2000 Elsevier Science B.V. All rights reserved.