The major advantages of this method are the following: (1)2-(dimethylamino)ethanethiol was used for the first time as the derivatization reagent for cyanide, and the process found to be very rapid and reproducible in a water matrix and under mild conditions; (2) the proposed method can sensitively determine cyanide to LOD of 0.02 mg L1 without interference from serious contaminants in surface water; and (3) this method offers a new gas chromatograph–tandem mass spectrometric method and easier derivatization procedure and opportunities for the cyanide analysis from less amount of real sample and extraction solvent than preceding chromatographic methods.