Thermal conductivity, high-temperature load-bearing resistance, reheat shrinkage, and porosity were determined on new pure oxide heavy refractories of alumina, magnesia, and stabilized zirconia. Alumina refractories were shown to be capable of lining furnaces for operation to 1900 "C., and magnesia and stabilized zirconia refractories to at least 23OOOC. The thermal conductivity of alumina refractories was found to vary directly with density, and four mixtures are described with conductivities ranging from 6 to 18 B.t.u. per hr. per sq. ft. per in. per "F. at 1800°F. Stabilized zirconia refractories, although having twice the bulk density of fire-clay brick, showed lower thermal conductivity. The uses and limitations of pure oxide heavy refractories are discussed.