Sensing and immobilization of uranyl ions have been studied by electrochemical methods using modified electrodes by a conducting polymer. polypyrrole doped with calixarenes. Cyclic voltammograms are examined for various combinations of electrodes and electrolytes at various pHs. Redox peaks. that are characteristics of uranyl ions, are enhanced by the modified electrode with polypyrrole doped by calix[6]arene-p-hexasulphonate. The modified electrode is found to immobilize uranyl ions by special treatments of the modified electrode. The results are discussed with the ability of high selectivity and immobilization of calixarene for uranyl ions.