AbstractPorous alumina catalyst supports have been prepared with pore volumes exceeding 1.0 mL/g, with most pores having diameters of the order of 3 μm and with surface areas exceeding 150 m2/g. They were obtained from dilute alumina gels having large concentrations of acid and very large concentrations of fluid. Attempts were made to dry the gel without collapsing the pore structure between the alumina particles. The catalysts were characterized by gravimetrical BET surface area, mercury porosimetry, X‐ray diffraction and scanning electron microscopy. Catalyst supports having these geometric properties should eliminate mass transfer restrictions during hydrocracking of petroleum residua, heavy oils and bitumen derived from oil sand deposi