XPS and AES are often used in corrosion studies to identify the chemical composition of the interface. Moreover, the last developments of the technology makes available lateral resolutions of 10 nm in AES and 10 µm in XPS, which is interesting for grain boundary corrosion or pitting corrosion. These techniques are also used to characterize the surface of electrodes in fuel cell systems, or mixed (alloys) electrodes used for environmental purposes. AES and XPS are good complement to classical electrochemical techniques (cyclic voltammetry, coulommetry) which give access to the current flowing through the interface, as they can identify the nature and the number of surface atoms, as well as their chemical environment. However, as XPS and AES are UHV-based techniques, the physical nature of the interface probed is different from the original solid-liquid one, and transfer in air can modify the sample surface. This paper shows selected examples of coupled UHV-electrochemical studies (adsorption, corrosion, electrocatalysis), using transfer systems, and describes the information which can and which cannot be extracted from such studies. The persistence of the constituents of the electrical double layer and the nature of the electrode metal on the reliability of the results is discussed. A description of some transfer systems, designed to minimize the experimental artefacts, is proposed.@footnote 1@ @FootnoteText@ @footnote 1@F. Reniers, J. Physics D: Appl.Phys.35 (2002)R169-R188.