The title compound, [UO(2)(C(33)H(38)N(2)O(2))(2)](CF(3)SO(3))(2).2C(5)H(5)N, has been obtained by reaction of U(IV) trifluoromethanesulfonate with p-tert-butyltetrahomodioxacalix[4]arene in pyridine. The uranyl ion lies on an inversion centre and is bound to two O atoms from each diphenoxide ligand, which gives the usual square-planar equatorial environment. The zwitterionic diphenoxide species results from nucleophilic attack by pyridine on the benzylic ether C atoms of the homooxacalixarene, assisted by initial U coordination to the ether groups, with subsequent metal oxidation giving the uranyl moiety.