The determination of the key geometric parameters used for high-frequency sonoreactor modeling has been studied. The methodology allowing the characterization of the different reactors built in our laboratory has been defined. The methods are : calorimetry, determination of the residence time distributions, the observation of the chemiluminescence of luminol and the degradations of a prototype molecule : pentachlorophenol. After characterization of the studied reactors, it seems that volumetric power, with equivalent emitting system, is the major parameter of the reactor’s performance.