A selective membrane electrode based on surfactant modified zeolite showed very good selectivity for thiocyanate anions over a wide variety of common inorganic and organic anions. The sensor displayed a near Nernstian slope of -58.9 +/- 0.9 mV per decade of the thiocyanate concentration. The working concentration range of the electrode was 1.00 x 10(-6) to 1.10 x 10(-1) M with a detection limit of 8.3 x 10(-7) M thiocyanate. The response of the sensor to thiocyanate remained constant in the pH range of 2.0-10.1. The best performance was obtained with a membrane composition in the ratio of 25.5% PVC, 64.5% dioctyl phthalate and 10% surfactant modified zeolite ZSM-5. The sensor was highly selective for thiocyanate over a wide variety of other anions and exhibited a rapid response time of <10 s over a period of 2 months with good reproducibility. Thus, this novel sensor may be applied as an indicator electrode in the argentometric titration of thiocyanate. (C) 2011 Elsevier B.V. All rights reserved.