A sensitive gas chromatographic mass spectrometric (GC–MS) method has been established for the simultaneous determination of acetamide (AA), propanamide (PA), and butyramide (BA) in surface and drinking water based on derivatization with 9-xanthydrol. Deuterated acrylamide was chosen as the internal standard for analyzing the water sample. The derivatization of AA, PA, and BA was performed directly in water and the reaction conditions (10.0-mM 9-xanthydrol, 0.5-M HCl, 20-min reaction time, and ambient temperature) were established. Under these conditions, the detection limit of the analytes was 0.03μgL −1 , and the interday relative standard deviation was less than 16% at concentrations of 1.0, 5.0 and 10.0μgL −1 . The proposed GC–MS method enables the reliable analysis of trace AA, PA, and BA in environmental water.