A new nitrate-selective coated-wire electrode based on the complex (6,8,15,17-tetramethyl-7H,16H-5,9,14,18-tetra-azidobenzo[b,i]-cyclotetra -decanato-(2-)-K (4)-N,N',N",N''') Ni(II) as the membrane carrier was developed. The electrode exhibits a good Nernstian slope of -57.8 +/-1.0 mV/decade and a linear range of 1.0 x 10(-5)-1.0 M for nitrate. The limit of detection is 5.0 x 10(-6) M. It has a fast response time of 15 s and can be used for more than four months. The selective coefficients were determined by the fixed interference method (FIM) and could be used in the 2.2-9.4 pH range. The electrode was employed as an indicator electrode for direct determination of nitrate in fresh water. (C) 2004 Elsevier B.V. All rights reserved.