Nano-sized particles research has become very important field in material science. Among the various nanomaterials, oxide nanoparticles have attracted increasing technological and industrial interest. This interest has mainly to do with their properties (magnetic, electrical, and catalytic properties). In this study, nanocrystalline Ni/ZnO particles were synthesized by ultrasonic spray pyrolysis and hydrogen reduction method. Stochiometric amount of nickel nitrate and zinc nitrate were used to prepare the corresponding solution. Particles were synthesized by hydrogen reduction of the aerosol droplets of the precursor solution under constant H-2 flow rate at 700 degrees C, 800 degrees C and 900 degrees C. Thermodynamics of the composite particle formation by hydrogen reduction/decomposition of metal nitrates were investigated by HSC software. Morphology, size, chemical composition and crystal structure of the particles were investigated by scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD). We have explored catalytic properties of nanocrystalline Ni/ZnO particles.