A triorganosiloxy end-capped organopolysiloxane, i.e., organopolysiloxane having a backbone consisting essentially of repeating (3,3,3-trifluoropropyl)methylsiloxane units and end-capped with triorganosiloxy groups is prepared by copolymerizing tris(3,3,3-trifluoropropyl)trimethylcyclo-trisiloxane with a silanol end-capped organopolysiloxane in the presence of an alkyllithium or lithium silanolate catalyst to form a silanol end-capped copolymer, and adding a trialkylsilyl triflate or strong acid in excess relative to the catalyst and a hexaorganodisilazane for effecting end-capping and neutralization.