The hydrotreating (HT) of Maya crude oil was carried out in a Parr batch reactor, using alumina-supported catalysts based on NiMo sulfides, carbides and nitrides, which were synthesized by temperature programmed reaction of the oxidic precursors. The catalysts were characterized by X-ray diffraction, N-2 physisorption, scanning- and high resolution transmission-electron microscopy. Next, catalysts with the best performance in thiophene hydrodesulfurization (HDS) were selected to be used in the HT of Maya crude oil. HT reactions were carried out at 320 degrees C and 70-80 kg/cm(2). All catalysts were sulfided ex situ with a mixture of CS2/H-2, prior to reaction. Products of reaction were analyzed by simulated distillation, sulfur and metal contents. Specific weight was also obtained, which was further used to calculate specific gravity and API gravity. Here, it was shown a synergistic effect by using Ni as promoter to Mo carbides and nitrides which is in contrast to previous reports. Moreover, during Maya crude oil HT, it was accomplished the enhancement of API gravity by using NiMo sulfide. Sulfur and metal removal was also successful using these materials, confirming that active phases based on NiMo nitrides and/or carbides could be considered as new HT catalysts for real feedstocks processing. (C) 2013 Elsevier B.V. All rights reserved.