The possibility of improving the selectivity of solid-state nitrate-selective electrodes by the application of the tetrathiafulvalene (TTF) or its nitrate salt (TTF(NO3)) as an intermediate layer between an electrical conductor and a polymeric membrane is demonstrated. The analytical performance of electrodes was investigated during potentiometric measurements. Fabricated sensors displayed a Nemstian slope (-58.85 mV/decade in the range from 10(-5.0) to 10(-1) M and -59.36 mV/decade in the range from 10(-6.0) to 10(-1) M for TTF- and TTF(NO3)-modified electrodes respectively), repeatable and reproducible standard potential and detection limit of 2.5 mu M (0.16 mgL(-1)) and 0.63 mu M (0.039 mgL(-1)) for TTF- and TTF(NO3)-based electrodes, respectively. The selectivity was considerably improved compared to a coated disc electrode or electrodes with intermediate layer based on carbon nanomaterials. Electrical parameters of the proposed sensors were tested by carried out current-reversal chrohopotentiometry. In the case of electrodes with the use of TTF or TTF(NO3) the potential drift decreases to 167 mu Vs(-1) or 16.6 mu Vs(-1) and the capacitance is 5.99 mu F or 60.3 mu F. The proposed sensors were successfully applied in analyzing nitrate concentration in water samples. (C) 2015 The Electrochemical Society. All rights reserved.