Reactions of di(1-naphthyl)methane (DNM) over Fe and FeS2 at 300-degrees-C were carried out to investigate the catalytic activities and selectivities of the two catalysts. Both catalysts showed high activities for the reaction of DNM but Fe catalyzed DNM hydrogenation whereas FeS2 catalyzed DNM hydrocracking. This difference can be ascribed to the presence of sulfur.