Nitrides of molybdenum, tungsten and vanadium supported on gamma-Al2O3 were prepared by temperature-programmed reaction with NH3 and tested as catalysts for hydrodeoxygenation of oleic acid and canola oil at 380-410 degrees C and 7.15 MPa H-2. The molybdenum nitride catalyst was found superior to the vanadium and tungsten nitrides for catalytic hydrotreating of oleic acid in terms of fatty acid conversion, oxygen removal and production of normal alkanes (diesel fuel cetane enhancers). The supported molybdenum nitride favoured the hydrodeoxygenation of oleic acid to n-C18H38 three times out of four compared to decarbonylation and decarboxylation. A 450-h long hydrotreating test performed at 400 degrees C and 8.35 MPa H-2 with Mo2N/Al2O3 and canola oil, indicated that oxygen removal exceeded 90% over the duration of the experiment and that the yield of middle distillate hydrocarbons (diesel fuel) ranged between 38 and 48 wt% (based on liquid feed). Crown Copyright (c) 2010 Published by Elsevier B.V. All rights reserved.