A green and efficient pathway for the synthesis of 3-acylindoles using a Brønsted acidic ionic liquid as a catalyst has been developed for the first time. The C3-acylation of N-unsubstituted indoles with acid anhydrides affords the desired products in good to excellent yields with high regioselectivity under microwave irradiation. Moreover, the Brønsted acidic ionic liquid can be recycled up to four times without significant loss of catalytic activity.