Thioamide derivatives of p-tert-butylcalixarene were used as ionophores in the development of solid-contact ion-selective electrodes based on conducting polymer poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT/PSS) which was synthesized by electrodeposition on the glassy carbon electrodes. The typical ion-selective membranes with optionally two different plasticizers [bis(2-ethylhexyl)sebacate (DOS) and 2-nitrophenyl octyl ether (NPOE)] were investigated. The potentiometric selectivity coefficients were determined by separate solution method (SSM) for Pb2+ over Cu2+, Cd2+, Ca2+, Na+, and K+. High selectivity toward Pb2+ was obtained. By applying two conditioning protocols, a low detection limit log(a(DL)) approximate to -9 was achieved. The fabricated ion-selective electrodes were used to determine Pb2+ concentration in environmental samples. The obtained results were compared to analysis done by inductively coupled plasma mass spectrometry (ICPMS).