In this study, a new terbium(III) membrane sensor was constructed based on 1,4-bis[o-(furan-2- carboxamidophenyl)]-1,4-dithiobutane (FCT) as a suitable materisl. The proposed membrane sensor was fabricated based on a membrane containing 2% sodium tetraphenyl borate (NaTPB) as an anionic additive, 66% dibutyl phthalate (DBP) as solvent mediator, 2% 1,4-bis[o-(furan-2- carboxamidophenyl)]-1,4-dithiobutane (FCT) as an ionophore and 30% poly vinyl chloride (PVC).The proposed Tb3+ electrode exhibits a Nernstian slope of 20.7 ± 0.2 decade of activity was demonstrated with a response time of 5 s, and has a lower detection limit of 7.5×10-8M.The linear range of the sensors was 1.0×10-7-1.0×10-2 M. It could be used in a pH range of 2.5–7.8.