Microwave assisted combustion method was used to synthesize nanocrystalline ZnxNi1-xFe2O4 from a stoichiometric mixture of corresponding metal nitrates and urea powders. The structural, chemical and magnetic properties of Ni-Zn ferrite was determined by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), infrared spectroscopy (FTIR), vibrating sample magnetometry (VSM) and DC conductivity measurements. Results showed that the material was spinel structure with a high purity with an estimated crystallite size of similar to 20 nm by X-ray line profile fitting. TEM analysis showed necked near-spherical particles with an average size of similar to 20 nm, reflecting highly crystalline nature of these nanoparticles. Magnetic properties showed anomalities as the Zn doping level increased. This has been explained and attributed to the relative positions of Ni, Zn, and Fe ions in the crystal lattice. (C) 2009 Elsevier B.V. All rights reserved.