A N3S5-azathiacrown ether has been newly synthesized in high yield. Electrode using this compound as ionophore shows high selectivity and sensitivity towards Ag+. The effect of plasticizers and ion-exchanger on the properties of electrode was also studied and detection limit of 3.8 x 10-8 M Ag+ was obtained. This sensor has a fast response time of <12 s and performs satisfactorily over a wide pH range of 3.6-8.2. The electrode was also successfully used as indicator electrode in the titration of Cl- in tap water.