To prepare a structure with a count of more than one p-tert-butylcalix[4]arene triketon unit, oligomer (3) was reacted with 25,26-diacetonyoxy-5,11,17,23-tetra-tert-butyl-26-28-dihydroxycalix[4]arene (2) and compound (4) was treated with chloro-acetone to obtain calix[il]arene units containing triketon groups. It was found that the polymeric calix[4]arene was selective to extract Li+ from an aqueous solution which contained Li+, Na+, K+, Ag+, Co2+, Ni2+, CU2+ and Cd2+.