Abstract: By means of the low temperature electrolysis with organic electrolyte and the radioassay method, the Ce content in various phases of steel, cast iron and aluminum was measured.With the same Ce content, more Ce is alloyed in cast iron and much more is alloyed in aluminum in comparison with steel.The coating-autoradiography shows that the alloyed Ce distributed among the pearlite is more than that among the ferrite in 16Mn or 25MnTiB steels. An enrichment of Ce was obviously observed to be segregated along the grain and dendrite boundaries in FeCrAl alloy.Ce distributes uniformly in the flaky graphite, yet variously in the nodular graphite. Ce is depleted from ferrite and pearlite surrounded by nodular graphite, and enriched in pearlite and ledeburite far apart from nodular graphite.Ce is obviously enriched along the grain boundaries in the as-cast aluminum.