A new Eu(III) PVC membrane sensor has been constructed by using 1,4-bis[o-(thiophene-2- carboxamidophenyl)]-1,4-dithiobutane (TCD) as a suitable ion carrier. The proposed electrode based on (TCD) with nitrobenzene (NB) as a solvent mediator in a poly(vinyl chloride) membrane matrix exhibited a near-Nernstian response to Eu3+ in the concentration range of 1.0 × 10−6 to 1.0 × 10−2 M with a slope of 19.5 mV per decade of activity of Eu3+, a relatively fast response of ~5 s in a wide pH range 2.7-8.8. The lower limit of detection was 6.7 × 10−7 M.