In this work, a highly terbium PVC-membrane sensor based on N-phenyl-2- (phenylcarbamothioyl) hydrazinecarboxamide as a suitable ion carrier was created. The resulting data illustrated that the electrode presents a Nernstian slope of 19.7 ± 0.5 mV per decade for the Tb3+ ions across a broad working concentration range from 1.0 × 10−6 to 1.0 × 10−2 M. The detection limit of the electrode is 5.6×10−7 M. It has a useful working pH range of 2.8 –8.5. The potentiometric response of the proposed electrode is independent of the pH of the solution in the pH range of 3.0 –7.5. The sensor possesses the advantages of short conditioning time, fast response time (~10 s), and especially, very good selectivity towards transition and heavy metal, and some mono, di and trivalent cations. The practical applicability of the electrode was demonstrated by its use the determination of Tb(III) ions in water solutions (tap water and river water) and in various binary mixtures.