The structure and magnetic properties ofnanocrystalline nickel ferrite powder NiFe₂O₄ has been investigated using two different preparation methods, including the ceramic technique and citrate method. The synthesized powders were characterized using X-ray Diffraction (XRD) for crystallite size, X-ray density and lattice parameter calculation. The results indicated that the citrate method gives the lowest value for the lattice parameter and crystallite size (60.6 nm) in citrate method and (73.8 nm) in ceramic method. Distribution of cations among the two interstitial sites (tetrahedral and octahedral sites) has been estimated by analyzing the powder X-ray diffraction patterns by employing Rietveld refinement technique, and the results reveal the existence of samples asinverse spinelwith cubic structure and Fd-3m space group.The morphological investigations using Field Emission Scanning Electron micrograph (FE-SEM) and High Resolution Transmission Electron Microscopy (HR-TEM).The elemental analysis of samples usingEnergy Dispersive X-ray Analysis (EDAX)  .Magnetic measurements of the samples at room temperature were carried out by means of vibrating sample magnetometer (VSM).