The construction and performance characteristics of ion-selective membrane electrodes for a newly found phenylpiperazine antidepressant, Nefazodone (NFN), based on its ion-pair complexes with phosphotungstate (PT), tetraphenylborate (TPB), tungstosilicate (TS) and reineckate (RN) in a poly(vinyl chloride) (PVC) matrix are described. The best ion-selective electrode for determination of NFN contains NFN-PT as the active material. This electrode exhibits a Nernstian response (62.6 0.4 mV per decade) in the range 1.5 x 10(-5) to 1.0 x 10(-2) M NFN.HCl in solutions. The selectivity of this electrode to NFN in the presence of a number of sugar molecules, cations and drugs is reported. The potentiometric standard addition method and the argentometric titration method are used to determine the NFN amount in pure solution.