Summary A simple colorimetric tube detector for the detection of 2-(dialkylamino)ethanethiols and V-series nerve agents in water and in aqueous solutions is proposed. The detector is based on the reaction of the compounds with a chromogenic Folin-Ciocalteu reagent yielding a blue coloured reduction product. The detection limit of 2-(dialkylamino)ethanethiols is 2.5 mg/l, measurement range up to 250 mg/l. The detection limit of the V (VX) agent is 10 mg/l. The method allows V agents and their precursors and hydrolysis products to be easily distinguished from G-series nerve agents.