The kinetics of the hydrodenitrogenation of o-toluidine has been studied between 330 and 370 degreesC at 5.0 MPa in a continuous microflow reactor over sulfided and fluorinated NiMo catalysts supported on alumina as well as silica-alumina. The silica-alumina-supported catalysts exhibited a higher hydrodenitrogenation activity than their alumina-supported counterparts. In situ fluorination promoted the hydrodenitrogenation activity by mainly enhancing the activity for the saturation of the aromatic ring. Kinetic parameters for the reaction network were obtained by fitting the experimental results with Langmuir-Hinshelwood equations. The reaction rate constants of the alumina- as well as silica-alumina-supported NiMo catalysts increase substantially after fluorination. The activation energies and the heats of adsorption are about the same over all catalysts. This indicates that the intrinsic activity of the active sites is not influenced by the in situ fluorination and by the support; only the number of hydrodenitrogenation sites is increased by a higher stacking of MoS2. (C) 2003 Elsevier Science (USA). All rights reserved.