Four extended runs, employing a CoMo/Al2O3 catalyst or a NiMoP/Al2O3 catalyst, were made with quinoline or decahydroquinoline as the feed to determine the kinetics of the vapor-phase hydrodenitrogenation (HDN) of quinoline at 613 K and 3.4 MPa. The data indicated appreciable inhibition of HDN by N-containing intermediates. Langmuir-Hinshelwood rate equations of the HDN network were used to fit the experimental data. It was necessary, first, to subdivide the network into smaller groups of certain species to obtain reasonable parameter values, which were then employed as estimates in the complete network. Three different types of active sites were required to achieve satisfactory fits to the data. It was found that an additional reaction path was also needed in the case of the CoMo catalyst that is not included in the usual HDN network. Propylbenzene was a minor product and was formed mainly from the dehydrogenation of propylcyclohexene. The CoMo catalyst was more active than the NiMo catalyst for the HDN of quinoline.