A critical aspect in the assessment of thermal and storage stability of jet fuels is the measurement of hydroperoxide concentrations. The accepted procedure for this determination employs manual titration with standard thiosulfate using a visually detected color change to detect the endpoint. In many fuels, particularly when stressed, intense coloration of the fuel prevents accurate visual endpoint detection. This problem can be overcome by using a potentiometric method of endpoint detection with an automatic titrator. These two techniques are shown to provide identical results. The method also specifies the use of CFC-113 (Freon TF) as the titration solvent. Since CFC-113 will not be available in the future, several other solvents have been examined. Isopropanol and pure hydrocarbons show promise as suitable replacements.