Cd 2 ion-selective electrode based on poly (styrene-co-acrylonitrile) copolymer (SAN) has been prepared using 8-hydroxyquinoline as an electroactive ionophore and dibutylphthalate as a plasticizing agent. The Cd 2 ion-selective electrode in presence of sodiumtetraphenylborate (NaTPB) as an anion excluder has exhibited a linear response within 4.46610 74 ยฑ1.0610 71 mol dm 73 activities of Cd 2 ions at a pH variation of 3.20 to 6.80. The observed response time of the prepared electrode was 12 seconds. The electrode has shown a reproducible Nernstian slope of 29 mV decade 71 activities of Cd 2 ions over a period of six months. The selectivity of the prepared electrode for Cd 2 ions in presence of a number of interfering cations is found to be high within the working range of the electrode. However, Pb 2 , Cu 2 and Mg 2 ions have shown interference when the activities of the Cd 2 ions in the solution were less than 1610 76 mol dm 73 .The electrode sensitivity and working range were found to be dependent on the concentration of the plasticizer and ionophore used in the preparation of the membrane electrode. The electrode can be used as an indicator electrode for the potentiometric titration of Cd 2 ions using ethylenediamine tetraacetic acid (EDTA) as titrant.