2,5-Dioxo-4-imidazolidinyl was used as an excellent sensing material in the preparation of a PVC membrane for a Ce(III)-selective sensor. The electrode shows a good selectivity for the Ce(III) ion with respect to most common cations including alkali, alkaline earth, transition, and heavy metal ions. The developed sensor exhibits a wide linear response with a slope of 19.6 ± 0.3 mV per decade over the concentration range of 1.0 × 10-6 to 1.0 × 10-1 M, while the illustrated detection limit is 5.7 × 10-7 M of Ce(III) ions. Moreover, it is concluded that the sensor response is pH-independent in the range of 3.1-9.8. The applications of the recommended electrode include the determination of concentration of Ce(III) ions in soil and sediment samples, validation with CRM's, and the Ce(III) ion potentiometric titration with EDTA as an indicator electrode. [ABSTRACT FROM AUTHOR]