Abstract: A method of frequency tuning a piezoelectric device and apparatus for the implementation thereof. A piezoelectric device having at least one resonating function is formed by two metallized electrodes facing each other, on a face of a plate made of a piezoelectric material. An arranging step arranges the plate, fitted with the electrodes, in a tuning position in proximity to an ion source. Then, an exposing step exposes the plate to an ion flux produced by the source and the ions etch the metal. A measuring step measures the resonant frequency of the resonating function while the plate is in a tuning position. Finally, a raising step raises at least one electrode exposed to the ions to an adjustable bias voltage to control the rate at which the metal on the electrode is etched.