Abstract: To provide a catalyst having hydrotreatment (hydrogenation, desulfurization and denitrification) performance that is equal to or superior to the prior art, as a hydrotreating catalyst for hydrocarbon oils, and a hydrotreating process for hydrocarbon oils using the catalyst. The catalyst comprises 10 to 40 mass % of at least one element of Group 6 of the Periodic Table, 0.5 to 15 mass % of at least one element of Groups 8 to 10 of the Periodic Table based on the oxide catalysts, and a 0.05- to 3-fold amount of an organic additive with respect to the total number of moles of the elements of Group 6 and Groups 8 to 10 of the Periodic Table, added to an inorganic porous support composed mainly of silica-alumina that comprises an oxide of a metal of Group 2 of the Periodic Table.

Abstract: Disclosed is a method of preparing a high-activity hydrotreating catalyst for hydrocarbon oil, where metals of Group VI (Mo and/or W) and Group VIII (Co and/or Ni) optionally along with phosphorus, and 0.3 to 3.5 molar times of the total molar amount of the metals of particular carboxylic acid(s) (tartaric acid, citric acid, etc.) and 0.1 times or more of the amount necessary for forming the active metals into their sulfides of particular organic sulfur compound(s) (mercapto-acetic acid, mercapto-succinic acid, etc.) are added to a material consisting essentially of at least one of inorganic acids and their hydrates, and they are kneaded shaped and dried at 200.degree. C. or lower. Using the catalyst, hydrotreatment, desulfurization and denitrogenation of hydrocarbon oil may be effected under mild conditions at a reduced operation cost.