The novel Mo/ZrO2 and CoMo/ZrO2 catalysts were prepared by impregnation of the monoclinic ZrO2 by the chelating agent nitrilotriacetic acid (NTA) assisted spreading of MoO3 with CoCO3 center dot xH(2)O and compared with samples prepared conventionally. The catalysts were characterized by X-ray diffraction, N-2 physisorption, O-2 chemisorption and activity in 1-benzothiophene hydrodesulfurization (HDS). The application of NTA during the catalysts preparation systematically increased the HDS activity by the factor 1.2-1.7.