The present study investigated sonochemical synthesis of Zr-ferrite nanoparticles under different operating parameters. In order to explore the sintering effect on ferrite phase formation, the synthesized ferrite particles were also calcined in the range of 200-900 degrees C. The obtained nanoparticles were characterized using XRD, FESEM, TEM, EDX, DRS, and VSM. The results revealed that the formation of ferrite phase needs external calcinations and in-situ microcalcination induced by transient cavitation is not sufficient for formation of spinel ferrite phases. The DRS results showed that it has a high capability of visible light absorption due to low band-gap energy in the range of 1.85 eV-1.93 eV. The change in band-gap energy is attributed to the crystalline size of the particle and the change of nature of the ferrite from amorphous to crystalline structure. While analysis of magnetic properties revealed that coercivity is dependent on calcination temperature and the solution pH. The highest coercivity and magnetic saturation were determined as 725 Oe and 0.750 emu/g; respectively. At higher pH, ferromagnetic behaviour with decreasing order in both magnetic saturation (M-s) and magnetic remanence (M-r) has been observed. To the best of our knowledge, this is the first report on magnetic properties of Zr-ferrite. (C) 2018 Elsevier B.V. All rights reserved.