In order to study the roles of the crystallite size of an active phase in a catalytic
reaction it is of utmost importance to be able to synthesize pure phases of crystallite in the
desired size range with a narrow size distribution. The method to produce a nano of Nickel
oxide ( ) is described. Nanoparticles (NPs) of are prepared by thermal decomposition of
freshly prepared nickel hydroxide by a sol gel route at 300°.This sample is characterized by Xray
diffractometer (XRD) and UV–visible spectroscopy. The average crystalline space or the
separation between atomic planes of () NPs is found to be about (2 - 5nm) and the average
of particle size is (9- 19 nm). According to our X-ray and neutron diffraction data, all NiO
powders are antiferromagnetically ordered at room temperature
