A new potentiometric chloride sensor based on the use of anion receptor 2-(1-H-imidazo [4,5-f][1,10]phenanthroline-2-yl)-6methoxyphenol (HIPM) in poly(vinyl chloride) (PVC) matrix is reported. Effect of various plasticizers: 2-nitrophenyloctylether (o-NPOE), di-n-butylphthalate (DBP), diethyl phthalate (DEP), dioctylpthalate (DOP), tri-n-butyl phosphates (TBP), chloronapthalene (CN) and cation excluder, cetryltrimethylammoniumbromide (CTAB) was studied. The best performance was obtained with a membrane composition of PVC: o-NPOE:HIPM: CTAB ratio (w/w, %) of 31:60:7:3. The sensor exhibits significantly enhanced selectivity towards chloride over the concentration range 5.0 x 10(-8) to 1.0 x 10(-1) M with a lower detection limit of 1.0 x 10(-8) M and a Nernstian slope of 59.8 mV decade(-1) of activity. Influence of the membrane composition and possible interfering ions was investigated on the response properties of the electrode. Fast and stable response, good reproducibility and long-term stability are demonstrated. The sensor shows response time of <10s; and can be used for about 3 months without any considerable divergence in their potential response. Selectivity coefficients determined with matched potential method (MPM) indicate high selectivity for chloride. The proposed electrode shows fairly good discrimination of chloride from anions. It was successfully applied to determination of chloride ion in packed drinking water. The electrode can be used in the pH range of 6.5-8.0 and mixtures containing up to 20% (v/v) non-aqueous content. It was used as an indicator electrode in potentiometric titration of chloride ion against silver nitrate. (C) 2009 Elsevier Ltd. All rights reserved.