A gas chromatographic (GC) method for the determination of trace amounts of oxinecopper (Ox-Cu) in water is described. A 500ml volume of sample water (pH 6.5-6.8) was passed through Sep Pak C₁₈ cartridge at a flowrate of 5ml/min. Then Ox-Cu absorbed on the cartridge was eluted with 4ml of methanol. After removing the solvent from the eluate, 2ml of 0.01M disodium ethylenediaminetetraacetate solution was added to the residue and the formation of 8-hydroxyquinoline (8-HQ) was facilitated by ultrasonic treatment and vigorous shaking. 8-HQ was extracted twice with 1 ml of benzene and determined with a flame-thermoionic detector (FTD)-GC using a megabore capillary column (DB-1). The recoveries of Ox-Cu from 6 kinds of sample water were 81-97% and the relative standard deviation were 2.5-5.7%. The limit of detection was 0.5μg/l.