Nickel ferrite NiFe2O4 nanoparticles have been prepared by sol-gel auto combustion. Two groups of samples were obtained from as-burnt and calcined powders by using various cooling conditions. The X-Ray diffraction (XRD) analyses confirm the single phase spinel structure for all samples. The grain sizes investigated by scanning electron microscopy (SEM) were found within the range of 70-100 nm. DC resistivities for different group of samples are strongly affected by cooling rate, showing the way how to control NiF2O4 electrical properties.