To improve the long-term performance of Ag/AgCl electrodes, which are commonly used as reference electrodes, a correction technique was developed that involves monitoring the dilution of the internal electrolyte. The dilution of the internal electrolyte was estimated using the UV/VIS absorbance of the electrolyte to which a spectrally active material (a triphenylmethane dye; TPMe) had been added. With this technique, the long-term performance of the Ag/AgCl electrode was investigated when the electrode was exposed to NaHCO3 solutions with various concentrations. We investigated effects of KCl and NaHCO3 on the UV/VIS absorbance of TPMe and the effects of TPMe and NaHCO3 on the potential of the Ag/AgCl electrode. Based on the experimental results, this technique was estimated to be applicable to the correction of the potential of Ag/AgCl electrodes as long as the KCl concentration of the internal electrolyte is maintained between 0.01 and 0.1 M. In NaHCO3 solutions, the correction technique was found to have another limitation determined by the contamination ratio defined as [NaHCO3]/[KCl]. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.098203jes] All rights reserved.