The characteristics of the surfactant-subtilisin Carlsberg (STC) complex are investigated on an enzymatic ester-exchange reaction in an organic solvent. The surfactant-STC complex exhibits a high enzymatic activity in various organic solvents although native STC hardly catalyzes the same reaction. The results reveal that the pH value and the surfactant concentration at the preparation stage have a prominent effect to ensure high catalytic activity of the enzyme complex in organic media. The high solubility of the surfactant-STC complex in organic media makes it possible to obtain direct information about the reaction mechanism by kinetic studies.