Ion selective electrode method is used for analyzing certain metal ions in a sample with ionophore as the link between two different solutions. The compounds 4-adipoybis (1-phenyl-3-methylpyrazolone-5) (H2AdBP) and 4-sebacoylbis (1-phenyl-3-methylpirazolone-5) (H2SbBP) are the same two types of ionophores but differ in the length of carbon chain. Both ionophores were used in potentiometric analysis of Nd3+ ion and showed that H2AdBP-Nd electrode had a slightly smaller detection limit, namely 1.91 x 10−5M with a sensitivity of 15.9 ± 2.2 mV/decade with a response time of 23 seconds, compared to the H2SbBP-Nd electrode with a detection limit of 2.88 x 10−5M, sensitivity of 21.9 ± 1.1 mV/decade and response time of 22 seconds. The effect of pH on the electrode performance was studied by varying the pH, concentration of ISA KNO3 and composition of the internal solution. Good electrode performance was obtained at pH 3 and the electrode sensitivity increased to pH 4. The electrode selectivity was carried out using a separate solution method (SPM) for the La3+, Ce3+ and Th4+ ions. The determination results of electrode pot showed that ESI-Nd electrode was not selective against La3+ and Ce3+ ions but selective to Th4+ with values < 1.