Choosing an adequate reference electrode for a three-electrode system in aqueous solutions involves understanding the specific application and the electrochemical environment. The principal mechanism of a reference electrode is to provide a stable and known potential against which the working electrode can be measured. Key factors include the electrode's stability, ionic strength of the solution, and compatibility with the working electrode material. Common types of reference electrodes include Ag/AgCl and saturated calomel electrodes, each with distinct advantages depending on the experimental conditions. The choice ultimately hinges on the desired accuracy, reproducibility, and the specific electrochemical reactions being studied.