This international standard specifies the evaluation methods for hydrogen content in UFB dispersions. The titration (oxidimetry) method can be used as a quick method to estimate the hydrogen content in hydrogen UFB dispersions. The detection limit is 0.1 mg/L, and the accurate range is between 0.2 mg/L and 1.6 mg/L. The existence of oxidizing or reducing substances in dispersions influences measurement accuracy. The gas chromatographic method features a considerably high accuracy range and the lowest detection limits. The existence of UFBs in water does not influence the measurement results. The existence of oxidizing or reducing substances in water does not affect the measurement accuracy either. However, the measurement procedure is time-consuming. Note: This international standard only provides a method for determining hydrogen contents in UFB dispersions and does not involve the specific effects of hydrogen UFB dispersion application.