Using nickel and ferric nitrates and citric acid, NiFe2O4 nanoparticles are prepared by a simple and cost-effective polyvinylpyrrolidone (PVP) assisted sol-gel auto-combustion method. The synthesised nanoparticles consist of single phase inverse spinel structure of NiFe2O4. The particles are in spherical shape with an average size of similar to 8 nm. The vibrational properties show tetrahedral and octahedral sites of NiFe2O4 nanoparticles. The super-paramagnetism is observed with magnetic saturation (M-s) of 50.4 emug(-1). (C) 2011 Elsevier Ltd. All rights reserved.