Abstract: Oxidation-reduction properties of Pd-Voxides supported on SiO₂ have been studied by TPR-TPO technique. The change in the structure of some components during the reduction-oxidation process has also been measured by IR-spectroscopy. The results indicate that a very small amount of Pd may lead to a significant decreasing in the reduction temperature of V₂O₅. The reduction temperature of the catalysts decreased with the increasing of Pd content, but the reoxidation temperature of the reduced catalysts don't change when the Pd-content varies. The oxidation temperature and the reduction temperature of the catalyst close with each other, when the content of PdOis 0.05%. So author concludes that the catalyst with Such a component is the most profitable for the above oxidation reaction. Two consecutive stages in ethylene oxidation were observed, one of them is a stage of adsorptive activation of ethylene and the second is astage of oxidation of ethylene. The reoxidation of reduced catalysts follows also two stages (at 170-260℃ and 360-400℃ respectively). The first stage refers to trapping pro.cess of oxygen in unchanged crystalline phase, and the second stage to the regeneration ,of the deactivited catalysts.