Classy carbon electrode modified with DNA-functionalized single-walled carbon nanotube hybrids by layer-by-layer was developed for the detection of 2,4,6-trinitrotoluene. The characteristic of the DNA-functionalized single-walled carbon nanotube hybrids was examined by atomic force microscope. Compares with single-walled carbon nanotubes-alone modified electrode, DNA-functionalized single-walled carbon nanotube hybrids-modified one exhibited the more superior ability of detecting 2,4,6-trinitrotoluene, including the higher sensitivity and the lower overpotentials, due to plenty of pi-electrons and hydrogen bond binding sites were provided. This modified electrode showed a fast response towards 2,4,6-trinitrotoluene and the detection could be finished within 15 s. A limit of detection of 0.5 mu g L(-1) was obtained by this modified electrode with a linear range at lest up to 800 mu g L(-1). Stability test showed an average relative standard deviation of 3.5% for 40 consecutive runs with a same modified electrode and the reproducibility of the responses of 2,4,6-trinitrotoluene was within 5.1% from one electrode preparation to another (n = 10). And also, the applicability of this modified electrode was demonstrated for the analysis of 2,4,6-trinitrotoluene in spiked groundwater. (C) 2009 Elsevier B.V. All rights reserved.