The prototype potentiometric chlorine gas sensor was constructed using Na3Zr2Si2PO12 (Nasicon) as a solid electrolyte, two-phase (1 - y)LaOCl-yNaCl as a sensing electrode, and 0.85Na(2)Ti(3)O(2)-0.15Na(2)Ti(6)O(13) as a reference electrode. Nasicon, 0.85Na(2)Ti(3)O(7)-0.15Na(2)Ti(6)O(13) two-phase system and LaOCl powders were prepared by solid-state reaction method. Two-phase materials (1 - y)LaOCl-yNaCl of different compositions were obtained by doping LaOCl with Na2CO3. The best preparation conditions were determined based on differential thermal analysis and thermogravimetry (DTA and TG). All the samples were studied by X-ray diffraction (XRD) analysis. Electrical conductivity of (1 -y)LaOCl-yNaCl was measured using electrical impedance spectroscopy (EIS). The source voltage (SV) of the fabricated cell was measured as a function of temperature (400-600 degrees C), Cl-2 partial pressure in the range 1-9 Pa and time. Constructed sensor shows the most effective performance at 500 degrees C and in Cl-2 pressure range of 3-9 Pa. (C) 2012 Elsevier B.V. All rights reserved.