PVC-based membranes of sulfamethoxazole diazonium resorcinol (SDR) as electroactive material with dioctylphthalate (DOP), Dioctylsebacate (DOS), o-Nitroph enyloctylether (o-NPOE) as plasticizing solvent mediators have been found to act as Ni 2+ selective sensor, the best performance was obtained with the sensor having a membrane of composition plasticizer:PVC:ionophore in the ratio 200:100:5 mg. The sensor exhibits Nernstian response in the activity range 5×10 −6 to 1.0×10 −1 M, performs satisfactorily over a wide pH range (5-9), with a fast response time (10 s). The sensor was found to work satisfactorily in partially different internal solution concentrations and could be used over a period of 2 months. Potentiometric selectivity coefficients determined by matched potential method (MPM) indicate excellent selectivity for Ni 2+ ions. The sensors could be used successfully in the estimation of nickel as an indicator electrode in potentiometric titration.