Hydrogenation-inducedmodification of magnetic properties has beenwidely studied. A Mg spacer layer with high hydrogen storage stabilitywas clamped in a Pd/Co/Mg/Fe multilayer structure to enhance its hydrogenstorage stability and explore the structure's magneto-transportproperties. After 1 bar hydrogen exposure, the formation of a stableMgH(2) phase was demonstrated in an ambient environment atroom temperature through X-ray diffraction. Lower magnetic couplingand enhanced magnetoresistance, compared to those of the as-grownsample, were observed using the longitudinal magneto-optical Kerreffect and a four-probe measurement. In this study, the hydrogenationstability of ferromagnetic multilayers was improved, and the conceptof a hydrogenation-based spintronic device was developed.