The power ultrasonic device described consists of an electric power ultrasound source (generator) and an electroacoustic transducer with a mechanical transformer (sonicator). The generator operates at the frequency 25 kHz and enables transfer of power up to 300 kW into a piezoelectric transducer. The changes in acoustic loading of the medium into which the sonicator emits are compensated by feedback. The device can be used in applications utilizing the cavitation process in liquids, e.g. degassing of liquids, water treatment (sterilization) in swimming pools, laboratory preparation of sonogels, initiation and acceleration of organic reactions. In modifications of technologies, the device can be used for delamination of tabular minerals (mica, specularite), for dispersing of pigments in a solvent and, after impedance adjustment, for milling of powdery materials.