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The subject of this thesis is the study of electrochemical promotion of catalysis (EPOC) also called non-Faradaic electrochemical modification of catalytic activity (NEMCA). In EPOC, the application of small current or potential on catalysts causes a significant non-Faradaic increase of catalytic activity. In this work, EPOC over platinum catalyst supported on yttria stabilized zirconia (YSZ) is investigated under ambient pressure and high vacuum (HV) conditions. Under ambient pressure conditions, a Permanent-EPOC behavior is obtained upon current interruption which is related to an oxygen storage process during polarization. In addition, a custom built HV setup is used to investigate the electrochemical kinetics and EPOC over Pt/YSZ cell. During anodic polarization, three types of oxygen storage locations are identified, i.e. Pt/YSZ interface, Pt/gas interface and Pt bulk. The saturation of the Pt/YSZ interface leads to the migration of the oxygen promoter over the Pt catalyst inducing the EPOC effect. The bulk storage takes place with prolonged polarization time. Upon current interruption, the stored oxygen is released onto the Pt surface leading to Permanent-EPOC or Persistent-EPOC which is determined by the stability of surface oxygen promoter. In addition, by using an anion emission configuration, the phenomenon of 16O- emission from the Pt surface is observed indicating that the surface promoter exists in the form of 16O- originating from the YSZ lattice. The application of isotopically labeled 18O2 allows discriminating the Faradaic process (16O from the YSZ) from the non-Faradaic process (18O from the gas phase). It’s found that the EPOC effect and metal support interaction (MSI) effect are different facets of the same phenomenon, i.e. the promoting effect of oxygen species from YSZ support on the catalytic reaction taking place over the catalyst surface. By application of a novel bipolar configuration, the imposed galvanostatic step causes significant enhancement of the catalytic rate over Pt nanoparticles which opens new possibilities for the application of nano-dispersed catalysts in electrochemical promotion.