NiMo catalysts supported on zeolite type Y modified with various anions were investigated. The structural properties and catalytic HDS activity of obtained samples were measured. It has been shown that change in zeolite crystal structure as a result of impregnation with anions was small. However, due to these anions considerably higher HDS activity of NiMo/NaY catalysts compared to samples without anions was observed. NiMo catalysts containing fluoride anions exhibited the highest activity. An explanation of the influence of anions on the HDS activity is also presented.