ISO 21087:2019 specifies the validation protocol of analytical methods used for ensuring the quality of the gaseous hydrogen (H2) at hydrogen distribution bases and hydrogen fuelling stations for road vehicles using proton exchange membrane (PEM) fuel cells. It also gives recommendations on the calculation of an uncertainty budget for the amount fraction.This document is established mainly for analysis done in laboratories after the sampling of hydrogen either at hydrogen distribution bases or at hydrogen refuelling stations. The specific requirements for on-line monitoring are not covered by this document.This document gives a list of suitable analytical techniques used to measure each impurity in hydrogen, according to the specification of hydrogen grade D defined by ISO 14687:—[1].Moreover, recommendations for keeping the integrity of the sample are also given in order to ensure the quality of the measurement. It also includes the requirements for reporting the analytical results.[1] Under preparation. Stage at the time of publication: ISO/DIS 14687:2018.