The deliverable D1.3 of THOTH2 project reports the findings of the Task 1.3 of the THOTH2 project. Chapter 1 is the introduction, where the urgency for a revision of normative regarding the metrology of the gas grid, both transport and distribution ones, is highlighted. Chapter 2 illustrates how the report has been prepared, detailing the work steps and interactions among partners and with experts involved in the European Technical Committee on the subject. Chapter 3 focuses on the current State of Art of normative regulations for gas grid metering. The actual Standard regulating the used gas meter typologies, gas properties measurements, composition measurements, leak detection, calculation and conversion are listed; for each of them the aspects that should be revised to account for H2 injection into the actual natural gas grid are evidenced. Chapter 4 collects the results from analysis in Chapter 3, including the answers to the survey distributed among partners on the subject, the conclusions drawn from similar projects and the information from the deputed committees to individuate the gaps that need to be covered by standards revision. The goal is to support the definition of a comprehensive European normative framework that regulates hydrogen injection into the natural gas grid. Finally, Chapter 5 summarizes the Report’s conclusions.