A family of trimetallic nitride endohedral metallofullerenes and their preparation are described. The trimetallic nitride endohedral metallofullerenes have the general formula A.sub.3-n X.sub.n @C.sub.m where n ranges from 0 to 3, A and X may be trivalent metals and may be either rare earth metal or group IIIB metals, and m is between about 60 and about 200. Further, the A.sub.3-n X.sub.n @C.sub.68, A.sub.3-n X.sub.n @C.sub.78, A.sub.3-n X.sub.n @C.sub.80 families of endohedral fullerenes are described. The trimetallic nitride endohedral metallofullerenes are produced by charging a reactor with a cored graphite rod that has been filled with a metal oxide graphite mixture. The metal oxides correspond to the metals for A and X. The graphite rod is arc discharged in a helium and nitrogen atmosphere to produce the desired trimetallic nitride endohedral metallofullerenes.