Аннотация:A superacid (H(OEt2)2)[Al(OtfBu)4] has been demonstrated as a highly active catalyst for the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL), which shows the highest catalytic activity among the known Brønsted acid catalysts in this process. With this superacid catalyst, the polymerization can be conducted in solvent and bulk conditions, either at elevated or at room temperature, and synthesis of high molecular weight polymers (> 100 kg/mol) is also successfully achieved.