Three nickel(II) Schiff base complexes derived from 4-amino antipyrine with 2-furaldehyde, 2-thiophene carboxaldehyde and 2-methoxybenzaldehyde has been synthesized and well characterized based on elemental analyses, IR, electronic spectra, molar conductance, and thermogravimetric analysis. Infrared spectra proved that three Schiff base chelates are coordinated to the nickel(II) ions as a bidentate fashion with ON and NS for the (2-furaldehyde and 2-methoxybenzaldehyde) and 2-thiophene carboxaldehyde, respectively. The molar conductance data reveal that all the Ni(II) chelates are non-electrolytes. The general formula of precursors nickel(II) complexes is [Ni(Ln)2(Cl)2] with 1:2 (Ni:L) molar ratio. These complexes were used as the primary nucleus to prepare nickel (II) oxide, NiO, nano-particles by thermal degradation in static air. The resulted NiO nano-particles have been discussed based on X-ray powder diffraction patterns, scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). All of the obtained NiO nano-particles are catalytically active in degradation process of hydrogen peroxide