A potentiometric ion selective electrode (ISE) was developed to determine the maprotiline, a tetracyclic pharmaceutical drug substance. Maprotiline-Tetraphenylborate ion pair was synthesized. Elemental analysis results showed that combination rate of Maprotiline-Tetraphenylborate ion pair was 1:1. The synthesized ion pair was used as sensing material in the structure of the electrode membrane. For membrane optimization, Polyvinylchloride (PVC) membrane ion selective electrodes were fabricated in different compositions using the synthesized ion pair and the potentiometric performance properties of these electrodes were investigated. We found that an electrode with a composition of 3.0% Maprotiline-Tetraphenylborate ion pair, 65.0% Dibutylphthalate, 32.0% Polyvinylchloride exhibited the best potentiometric performance properties. The linear working range of this electrode was 1.0 x 10(-5)-1.0 x 10(-2) M and slope in 10-fold concentration change was 55.4 mV; detection limit was 5.0 x 10(-6) M, pH working range was 3-5; and finally response time was 5 s. The electrode has demonstrated a highly repeatable potentiometric response. The maprotiline content of two different pharmaceutical tablets that are used to treat depression was determined using this electrode. The obtained results were compared with the results obtained by the GC method, which is our comparison method. We found that the results obtained using the potentiometric technique is consistent with the results obtained using GC method at 95% confidence level.