A method and apparatus for initiating and maintaining an abnormal glow volumetric sonoplasma discharge (VSPD). With certain parameters of the electrical discharge and of the intensity of elastic vibrations, it is possible to initiate VSPD within a cavitating liquid medium. The mechanism for the initiation of VSPD is related to the breakdown of gas phase microchannels formed by growth cavitation bubbles. The method for continuous processing uses elastic vibrations in the frequency range 1-100 kHz with enough intensity for the development of cavitation phenomena; these vibrations are introduced into the liquid phase working medium, and a source of direct, alternating, high frequency and ultrahigh frequency electric field in liquid provides the initiation and stable glow of VSPD. Resulting VSPD is characterized by volumetric glow in the frequency range of visible light and ultraviolet radiation in the entire cavitational-electric field and has a rising volt-ampere characteristic curve.