New magnetic materials containing cerium, iron, and small additions of a third element are disclosed. These materials comprise compounds Ce(Fe12−xMx) where x=1-4, having the ThMn12 tetragonal crystal structure (space group I4/mmm, #139). Compounds with M=B, Al, Si, P, S, Sc, Co, Ni, Zn, Ga, Ge, Zr, Nb, Hf, Ta, and W are identified theoretically, and one class of compounds based on M=Si has been synthesized. The Si cognates are characterized by large magnetic moments (4πMs greater than 1.27 Tesla) and high Curie temperatures (264≦Tc≦305° C.). The Ce(Fe12−xMx) compound may contain one or more of Ti, V, Cr, and Mo in combination with an M element. Further enhancement in Tc is obtained by nitriding the Ce compounds through heat treatment in N2 gas while retaining the ThMn12 tetragonal crystal structure; for example CeFe10Si2N1.29 has Tc=426° C.