Binary NiMo, CoMo, NiW, and CoW transition-metal oxide catalyst precursors, were synthesized through a hydrothermal reaction, and highly-loaded hydrodesulfurization (HDS) catalysts were prepared by mixing the precursors with an alumina gel, calcination and sulfidation. The transition-metal oxide catalyst precursors and highly-loaded sulfide catalysts were characterized by XRD, N-2 adsorption-desorption, XRF, and HRTEM. Dibenzothiophene and fluid catalytic cracking (FCC) diesel were employed to evaluate the HDS performance. The crystalline phases of ammonium nickel (or cobalt) molybdate were detected in the NiMo (or CoMo) oxide catalyst precursors, while quasi-amorphous phases were observed for the CoW and NiW oxide precursors. In the sulfided HDS catalysts, typical MoS2 or WS2 phases were observed by TEM, while XRD demonstrated that Ni and Co sulfides were present, in accordance with HRTEM results. The catalytic results showed that the binary transition-metal CoMo sulfide catalyst exhibited high direct desulfurization activity and that the NiMo sulfide catalyst had higher HDS and hydrodenitrogenation activities toward the FCC diesel than the other catalysts, with conversions of higher than 99.1% and 99.7%, respectively. (C) 2015 Elsevier Ltd. All rights reserved.