As shown previously, an unsupported Fe-Mo sulfide catalyst is quite selective toward hydrodenitrogenation (HDN) relative to hydrodesulfurization (HDS). This paper is primarily concerned with the activity enhancement of that catalyst. It is shown that the HDN and HDS volumetric activities of the Fe-Mo catalyst can be significantly increased by promotion with nickel or cobalt. The increased activities are much higher than those observed with existing commercial catalysts. This was observed in tests with a petroleum distillate feed. The overall HDS kinetics are catalyst dependent; theoretical explanations for such a dependence are given.