Poly o-toluidine zirconium(IV) iodosulfosalicylate (PTZIS) is a hybrid inorganic-organic composite cation exchanger, which was synthesized by mixing an organic compound, poly o-toluidine, into the matrices of zirconium(IV) iodosulfosalicylate on the basis of distribution coefficient K-d,K- the material was found to have high affinity for adsorption of Cr(III) ion. Due to is CR(III) selective nature ion exchanger was used as an electroactive material for preparation of an ion-selective membrane electrode. The physical properties of membrane were determined by XRD, SEM, and AFM analysis, which indicates that PVC-based Cr(III) ion selective memrbrane is amorphous and porous in nature. The electrode responds to Cr(III) in a linear range from 3.16 x 10(-6) to 1 x 10(-1) M with a Nernstian slope of 22 +/- 0.5 mV per decade change in concentration and a detection limit of 1.584 x 10(-6) M. The life span of the electrode is found to be 12 weeks. The proposed electrode shows satisfactory performance over a pH range of 30-70, with a fast response time of 10s. The sensor has been applied to determination of cr(III) ionsin water samples of different origins. The sensor has been used as an indicator electrode in potentiometric titrations of Cr(III) ion with EDTA.