<p>A method is proposed for the ultrasonic cavitation spraying of liquid with an increased efficiency and with formation of smaller-size droplets, compared to those provided by the known methods. The method proposed is based on the formation of cavitation bubbles in the liquid kept under pressure and acted upon by ultrasonic vibrations. A mathematical definition of the process has been developed and its critical parameters (the amplitude of the ultrasonic vibrations and the hydraulic pressure) at which minimum-size droplets are formed were revealed. For the practical realization of the method, a cavitation sprayer has been designed and the sizes of the droplets formed were investigated depending on the parameters of the process. The cavitation sprayer designed provides, at an ultrasonic vibration frequency of 24.3 kHz and a hydraulic pressure of 9∙10⁵ Pa, the formation of droplets of size not larger than 45 μm. In this case, the rate of a liquid flow is smaller than 10 mL/s. For comparison, a known method of ultrasonic spraying of liquid at a frequency of 22–24 kHz and the existing ultrasonic sprayers, working at this frequency, give no way of forming droplets of size smaller than 100 μm.</p>