Abstract: A process for expanding tobacco is provided which employs carbon dioxide gas. Tobacco temperature and OV content are adjusted prior to contacting the tobacco with carbon dioxide gas. A thermodynamic path is followed during impregnation which allows a controlled amount of the carbon dioxide gas to condense on the tobacco. This liquid carbon dioxide evaporates during depressurization helping to cool the tobacco bed uniformly. After impregnation, the tobacco may be expanded immediately or kept at or below its post-vent temperature in a dry atmosphere for subsequent expansion.