Nickel ferrite (NiFe(2)O(4)) nanoparticles are prepared by a polyvinyl alcohol (PVA) assisted sol-gel auto-combustion method. The structure, composition, morphology and magnetic properties of the gel precursor are characterized by powder XRD, FT-IR, TGA, HR-SEM, TEM, HR-TEM and VSM. XRD confirms the formation of single-phase nickel ferrite with space group of Fd3m and inverse spinel structure. The vibration properties of nanoparticles are analysed by FT-IR spectrum. The thermal decomposition of the gel precursors is investigated by TGA. HR-SEM and TEM images show that the particles have spherical shape with particle size in the range of similar to 30 nm and consistent with XRD result. The magnetic properties of these nanoparticles are studied for confirming the ferromagnetic behaviour at room temperature. (C) 2011 Elsevier Ltd. All rights reserved.