A series of nickel-molybdenum catalysts incorporated on alumina modified with sulfate and phosphate ions was studied. Decomposition of isopropyl and diacetone alcohols and ethylbenzene and hydrofining of coal liquid were used as test reactions. The effect of support modification with phosphate and sulfate ions on the activity of NiMo varied. Incorporation of these ions at the concentrations used led to a decrease in acidity of the catalyst surface which increased with increasing concentration of the modifier. Phosphate ions raised the dehydrogenation activity, whereas sulfate ions hardly affected it. Both ions caused a significant decrease in HDN activity for coal liquid which diminished with increasing concentration of the ions. They also caused a slight decrease in HDS activity which however did not depend on their concentration.