It is very important to determine the structure at an electrode/electrolyte interface in situ not only for fundamental surface science but also for the applications related to nanotechnology. Surface X-ray scattering (SXS) technique is one of the most promising methods to determine the interfacial structure with a high space resolution in situ. Here we focus on the SXS technique, which is able to probe an atomic/molecular structure at buried interfaces, such as those of importance in electrochemistry. As an example, we described our results about the structural analyses of the electrochemical deposition processes of Pd and Ag on Au single crystal electrodes using in situ SXS technique.