The lipase-catalyzed butanolysis of triolein was carried out in an ionic liquid, methyltrioctylammonium trifluoroacetate (MTOATFA). The addition of 80% MTOATFA to the reaction system gave the best result in terms of alcoholysis rate. The final product (butyloleate) was selectively extracted from the reaction mixture using supercritical carbon dioxide. The present method is expected to be applicable to the lipase-catalyzed alcoholysis of triacylglycerols.