In this study, palm shell activated carbon modified with task-specific ionic liquid was used as a novel electrode component for the potentiometric determination of cadmium ions in water samples. The proposed potentiometric sensor has good operating characteristics, including relatively high selectivity towards the Cd (II) ion, a Nernstian response to Cd (II) ions in a working concentration range of 1.0 × 10−9–1.0 × 10−2 M, with a reasonable detection limit of 1 × 10−10 M and a slope of 30.90 ± 1.0 mV/decade. No significant changes in electrode potential were observed when the pH was varied over the range of 4–9. A direct technique based on the use of ion-selective electrode potentiometry has been developed in our laboratory for the study of reaction kinetics and kinetic methods of analysis by continuous monitoring of the rate of production or consumption of an ion. The apparent adsorption rate constant was estimated assuming pseudo-second-order kinetics. Additionally, the proposed electrode has been successfully used for the determination of the cadmium content in real samples without a significant interaction from other cationic or anionic species.