Abstract: Method of enhancing the catalytic effectiveness of rhodium to reduce nitric oxides: (a) preparing a polymer modifier (molecular weight of 500-50,000) by controllably reacting amine [mono-2-hydroxyl ethyl amine and di-2-hydroxy ethyl amine] with epoxy resin (two or more epoxide groups per molecule) to form a soluble adduct and adding to the adduct a solvent to form a homogeneous amino polymer solution; (b) coating a granular support material (gamma alumina) with rhodium chloride and/or rhodium nitrate compounds; and (c) mixing the coated support material with added amino polymer solution to the support material either prior to or subsequent to step (b) and heating the mixture of polymer solution, support material, and rhodium chloride and/or rhodium nitrate compounds to evaporate the solvent and to decompose and eliminate the polymer, leaving the coated support material with rhodium in a morphologically changed condition devoid of amino polymer but having enhanced catalytic effectiveness for promoting reductio