Abstract: A self-contained electric power driven bolt actuator unit for installation with a high security door locking mechanism comprising a housing adapted to be mounted on the door in operative association with the lock mechanism, a rotatable actuator shaft being mounted in the housing and connected at one end with a bolt actuating cam, an electric motor connected to drive the actuator shaft through a friction driving connection, a manually operable knob for overriding the actuation of the bolt by the cam independently of the motor, and switching means operable upon predetermined rotation of the actuator shaft in each direction of its rotation to reverse the driving direction of said electric motor and for indicating the operative position of the bolt of the locking mechanism.