Asphaltenes precipitated from an Arabian Mix vacuum residue were hydrocracked in a batch autoclave at 435 and 460 degrees C for 5-90 min. Experiments without catalyst, with modified red mud and with an industrial Co Mo/Al2O3 catalyst were compared. The products were fractionated into gas, naphtha, oil asphaltenes and coke. Feed asphaltenes and several product fractions were characterised by elemental analysis, by average molecular mass and by H-1 n.m.r. Due to the hydrogenation activity, both catalysts caused - with similar efficiency - the decrease of coke formation and the increase of quantity and quality of oil.