Applications of the synchrotron X-ray scattering technique to electrochemistry problems are briefly reviewed ranging from submonolayer level phenomena, through nanometer size phenomena, to submicron size phenomena; that is, covering the full range of the 'interphase' at an electrode surface. The examples include, (i) incipient oxidation/reduction of platinum single crystal surfaces; (ii) submonolayer/monolayer level oxidation/reduction of ruthenium dioxide single crystal surfaces; (iii) copper passivation/ depassivation; and (iv) anodic formation of porous silicon and silicon dioxide layers. The design of several X-ray/electrochemical cells is also described.