Abstract: The invention relates to an improved silver/silver-chloride reference electrode adapted for use in aqueous corrodent solutions at high temperatures and high pressures. The reference electrode provides a useful standard for measuring electrochemical phenomena related to the corrosion process so that metals can be compared on a thermodynamically useful scale. The formation of bubbles within the reference electrode, which can cause open circuit conditions, is substantially avoided by equalization of internal and external pressure through the use of a heat sealing vent means within the electrode body. Ionic conduction between the electrolyte contained within the reference electrode and the corrodent solution is controlled by a bridge containing tightly gripped fibers which are subjected to additional compression during heating and subsequent pressurization.