Polysulfone (PS), a non-conductive polymer, is employed as an alternative material to polyvinyl chloride (PVC), the most used polymer in the design of ion-selective electrode (ISE) membranes to date. A nitrate-ISE is chosen as a model electrode to study the efficiency of PS as a polymer matrix of the membrane. Tetra-octyl ammonium nitrate is used as ionophore and 2-nitrophenyl octyl ether as plasticizer. The polymer/plasticizer/ionophore ratio is optimized and the analytical performance parameters of the prepared electrodes are evaluated. The electrodes show a slope between 45 and 60 mV/decade (depending on the calibration medium and membrane composition). A linear range response between 1.0 × 10-4 and 3.0 × 10-2 M, and a lifetime of at least 1 month are obtained. The electrodes exhibit good selectivity for nitrate in respect to other anions.