Many important processes take place at solid/liquid interfaces. To understand these processes, in situ real-time evaluation of the geometric, electronic, and molecular structures at solid/liquid interfaces at the atomic and molecular levels is essential. Owing to the presence of the liquid, however, techniques such as electron microscopy and low-energy electron diffraction, which are powerful tools for surface structural analysis in vacuum, cannot be used for solid/liquid interfaces. In this review, various techniques applicable to solid/liquid interfaces, including scanning probe microscopy, synchrotron-radiation-based X-ray techniques, and nonlinear spectroscopy, are briefly described. The characterization of the electrodeposition process of Pd layers on Au single-crystal electrode surfaces is presented as an example to demonstrate the importance of using multiple techniques in an integrated manner to understand the processes at solid/liquid interfaces.