We report the synthesis, structural and magnetic properties of Ni1.5Fe1.5O4 ferrite nanoparticles. The pH value during coprecipitation from metal nitrates solution has been varied in the range 1-12. The samples after coprecipitation have been annealed at different temperatures to study thermal effect on crystalline phase and grain growth process. A detailed microstructural study has been performed using X-ray diffraction (XRD), Fourier Transform Infra-red Spectroscopy (FTIR), Scanning electron microscopy (SEM) attached with Energy dispersive analysis of X-ray (EDX) spectrometer, and Micro Raman Spectroscopy. XRD pattern showed formation of single phased cubic spine] structure above certain annealing temperature that strongly depends on the pH value during coprecipitation. Analysis of the FTIR and Raman spectra of the samples prepared at different pH values indicated ordering of cations in A and B sites of the cubic spinel structure. EDX data indicated Ni deficiency for the samples prepared at pH 2. Minor hematite (alpha-Fe2O3) phase has been identified for the samples coprecipitated at pH 4 and 6, in addition to the major cubic spine] phase. The samples of Ni1.5Fe1.5O4 have shown soft ferromagnetic character at room temperature and ferromagnetic parameters varied in a wide range with pH value at which sample was coprecipitated. (C) 2014 Elsevier B.V. All rights reserved.