This Communication describes the Cu(OTf)(2)-mediated fluorination of aryltrifluoroborates with KF. The reaction proceeds under mild conditions (at 60 degrees C over 20 h) and shows a broad substrate scope and functional group tolerance. The Cu is proposed to play two separate roles in this transformation: (1) as a mediator for the aryl-F coupling and (2) as an oxidant for accessing a proposed Cu-III (aryl)(F) intermediate.