Influence of hydrogen partial pressure on hydrodenitrogenation (HDN) of pyridine, aniline and quinoline was examined over Ni-Mo-P/alumina catalyst. Pyridine, aniline and quinoline are representative nitrogen compounds found in coal-derived Liquids. HDN of aniline was more enhanced by increasing hydrogen partial pressure than HDN of pyridine. The greater the adsorption strength of nitrogen compounds onto catalyst surface, the lesser is the effect of partial pressure of hydrogen. When the hydrogen partial pressure increased, quinoline HDN improved further with hydrogen sulfide than without hydrogen sulfide. The differences in the influence of hydrogen partial pressure on the quinoline HDN reactions were also interpreted in terms of the differences in the adsorption strengths of nitrogen compounds produced in HDN reactions onto catalysts.