This chapter focuses to hydrogen (H) loadingH loading in metals with consideration of problems or notes for investigation of H behavior in a metal depending on H loadingH loading methods. For the H loading, usually, gaseous or electrochemical chargingElectrochemical charging is employed, both of which are somewhat different from the H entryH entry into practical metals subjected to HE mostly caused by H uptake duringWater (HO) waterWater corrosion corrosionCorrosion. Artificial and intensive H loading makes the H concentrationH concentration in the loaded metals high enough to detect and analyze quantitatively, while the H uptake by the waterWater (HO) corrosionCorrosion is generally very slow and its concentrationConcentration is rather low except hydrogen accumulated or trapped at near surface regions and particular sites in bulk, such as defectsDefect, impurities, precipitatesPrecipitate, inclusionsInclusion, grain boundaries. Nevertheless, we have to use the intensive H loading, because of hard detection of H in metals. The importance of H releaseH release after the loading is noted on the analysis of H kineticsKinetics of the intensively loaded.