This study reports an electrochemical approach for an assay of trinitrotoluene (TNT) in water samples. This assay is based on the electrochemical reduction of TNT at a natural mineral, attapulgite, modified glassy carbon (attapulgite/GC) electrode. To detect TNT, TNT is first accumulated on an attapulgite/GC electrode by holding the electrode at a constant potential of 0 V versus Ag/AgCl for 40 s in an aqueous TNT solution. Next, the attapulgite/GC electrode with accumulated TNT is transferred to a fresh PBS solution (0.1 M, pH 7.0, without TNT), where the TNT reduction current at -0.36 V versus Ag/AgCl in a linear sweep voltammogram (LSV) shows a linear response to TNT concentrations in the aqueous solution from 1 to 200 ppb with a correlation coefficient of 0.998 and a detection limit of 0.2 ppb at a signal/noise (S/N) of 3. Moreover, the attapulgite/GC electrode displays high stability, good anti-interference ability to certain common interferents in real water samples, and reliable detection precision. Along with the abundance, low price, and environmental friendliness of attapulgite, the developed electrochemical sensor for the TNT assay has great potential for the practical determination of TNT levels in real water samples. (C) 2016 Elsevier B.V. All rights reserved.