The effect of hydrogen on the magnetic susceptibility of CeNi 4Al has been investigated. It is observed that following a hydrogen absorption-desorption cycle, without exposing the sample to air, the magnetic susceptibility of CeNi 4AlH 0(I) increases over that of CeNi 4Al. If, after hydrogenation, the sample is kept in the air and then hydrogen removed, the increase in susceptibility of CeNi 4AlH 0(II) is even larger. Magnetic precipitation of Ni due to the presence of O 2 and H 2O is thought to be responsible for this behavior. An increase in susceptibility of CeNi 4AlH 3.7 over that of CeNi 4Al is also observed and attributed partly to the tendency of valence change of cerium from 4+ toward 3+.