The hydrogen storage properties of multi-component magnesium-base alloys have been studied and it was found that Mg 0 . 8 3 3 Ni 0 . 0 6 6 Cu 0 . 0 9 5 Ml 0 . 0 0 6 has good hydriding/dehydriding properties (Ml stands for La-rich mischmetal). Based upon the investigation of the relation between hydriding/dehydriding behaviour and micrographic morphology, it was found that the morphology of some phase constituents in the alloy has an important influence on the hydriding/dehydriding processes. The effect of surface segregation of elements Ni, Cu and RE (rare earth) on kinetics of hydriding/dehydriding processes has been examined by means of AES and metallographic observations. On the basis of all these experimental observations, a model for the hydriding/dehydriding processes of the multi-component magnesium-base alloys--the model of surface segregation and interface-microcrack passages--has been proposed.