Molybdenum carbide catalysts supported on carbon nanofibers (beta-Mo2C/CNF) were synthetized employing different carburization parameters: five temperatures (550-750 degrees C) and four heating rates (1-10 degrees C/min) were tested. The carburization process of the Mo precursor in the catalysts was studied by thermogravimetric analysis, X-ray diffraction, X-ray photoelectron spectroscopy, N-2 physisorption, inductively coupled plasma optical emission spectrometry and transmission electron microscopy. The formation of the carbide phase was confirmed by the presence of the oxycarbide and carbide phases which were observed on the surface of all catalysts. Higher carburization temperatures resulted in an increase of the carbide phase content and crystal size at the expenses of the oxycarbide phase disappearance. High carburization temperatures and low heating rates were needed in order to obtain well-defined beta-Mo2C crystals over the catalysts, which involved a substantial improvement of their catalytic activity in the hydrodeoxygenation of guaiacol.