Nanoparticles of NiFe2O4 are prepared through sol-gel auto combustion method at two different conditions namely pH 7 and 8. The grain sizes of the prepared ferrites; are found to be in the range 24-31 nm. The optimal pH value for the preparation of single phase polycrystalline NiFe2O4 is determined by subjecting the samples to XRD (X-ray diffraction), FTIR (Fourier transform infrared spectrometry) and DSC (differential scanning calorimeter) analysis. The structural morphology of the nanoparticles is investigated using SEM (scanning electron microscope). Magnetization measurements are carried out using VSM (vibrating sample magnetometer). The studies show the formation of single phase nanoparticles of NiFe2O4 when prepared by maintaining the pH value of the precursor solution as 8. It is claimed that NiFe2O4 is synthesized directly after the completion of the combustion process and it possesses a high degree of crystallinity. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.