Nanocrystalline Ni-Zn ferrite (NiZnFe2O4) Was directly produced by high energy ball milling of stoichiometric mixture of ZnO, NiO, Fe2O3 powders. X-ray powder diffractometry (XRD), scanning electron microscopy (SEM), simultaneous thermal analysing (STA), Fourier transform infrared spectroscopy (MR) and vibrating sample magnetometer (VSM) were carried out to characterize the structural, chemical and magnetic aspects of NiZnFe2O4 compound. The formation of NiZnFe2O4 phase appeared to involve two stages: development of Zn ferrite by diffusion of ZnO in Fe2O3 followed by diffusion of NiO in Zn ferrite to form Ni-Zn ferrite. The crystallite size of final product after 60 h of ball milling time was estimated to be 18 nm which increased to 45 nm after annealing at 800 degrees C for 4 h. After annealing of ball milled powders, the saturation magnetization was increased and coercivity was decreased as lattice defects and internal strain reduced. (C) 2009 Elsevier B.V. All rights reserved.