Abstract: New catalyst for hydrocarbon conversion of organic feedstocks and method of preparing such catalyst. Catalyst is a composite made up of an inorganic oxide, wherein at least 50 weight percent of said inorganic oxide is silica and/or alumina, said matrix having dispersed therein a particulate crystalline aluminosilicate carrying rare earth cations, said composite catalyst having rare earth impregnated therein in an amount of from about 1 to 6 percent by weight (expressed as RE.sub.2 O.sub.3), this amount being over and above the rare earth level attainable by ion exchange alone.