In this paper Zn0,4Fe2,6O4 nanoparticles have been prepared by co-precipitation method. Ferrite nanoparticles are characterized by thermogravimetric and differential thermal analysis (TG–DTA). The crystalline structure of the zinc-doped magnetite nanoparticles have been studied with a help of X-ray diffraction (XRD). The samples show cubic inverse spinel structure with rang size of 9 to 26 nm.