The magnetization of the metal hydrides GdFe3Hx (x=0∼3.6) and Dy6Fe23Hx (x=0∼20.3) was measured in magnetic fields up to 29 T at 77 K. For these measurements the hydrides were prepared in situ in a glass holder with gradually varying hydride composition x at room temperature. For each system the magnetization curve varied systematically with hydrogen content. The dependence of magnetization on hydrogen content is discussed.