The electrical resistivity, resonant, antiresonant frequencies, diffusion coefficient of oxygen vacancies and elastic compliance were studied as a function of soaking time for a series of samples of CoZn ferrites. The increase of the soaking time decreases the electrical resistivity due to the formation of more Fe 3+ at octahedral sites. The diffusion coefficient increases when the structural vacancies increase with the soaking time. The elastic compliance increases due to the decrease of the anisotropy constant by increasing soaking time. The decrease of the domain wall thickness by increasing the soaking time makes it to vibrate at lower frequencies. The sintering time has an important role in determining good ferrite transducer for ultrasonic generator.