Abstract: The synergetic effect between Ni₂P/Al₂O₃ and MoS₂/Al₂O₃ catalysts on their performance in the hydrodenitrogenation of quinoline was proved by a simplified experimental design and explained by the remote control model through a migration of hydrogen spillover. The results indicated that the synergism factor of Ni₂P and MoS₂ is slightly higher than that of NiS_x and MoS₂; it decreases with the increase of reaction temperature. Since the spillover hydrogen with Ni₂P can increase the amount of hydrogenation active sites of MoS₂, the hydrogenation rate of 1,2,3,4-tetrahydroquinoline and 5,6,7,8-tetrahydroquinoline to decahydroquinoline over the Ni₂P/Al₂O₃ and MoS₂/Al₂O₃ catalyst system is then greatly enhanced; as a result, Ni₂P is a superior promoter for MoS₂ catalyst for hydrodenitrogenation.