An efficient and operationally simple method for chemical decontamination of sulfur mustard (HD) has been reported herein. A chlorine-bearing reagent N,N-dichlorourethane was developed to deactivate HD in aqueous (acetonitrile/water, 80/20) medium. This decontamination reaction was monitored by gas chromatography-mass spectrometry and NMR spectroscopy. This reagent is highly efficient, stable, economical, and easy to synthesize and leads to instant decontamination of HD. The reaction was found to instantaneously and completely convert HD to innocent products at different temperatures (-20 to 40 degrees C).