In this work, some haloacetic acid compounds were extracted from aqueous samples using single drop microextraction. Extraction was performed using 1.8 µL of 1-octanol droplet including 10% triflouroacetic anhydride hanging from needle tip of a 10 µL GC syringe from 3 mL sample solution. Monochloro, dichloro, trichloro, monobromo and dibromoacetic acid were studied compounds. Haloacetic acids in extracted sample were derivatized using octanol as derivatization reagent and triflouroacetic anhydride as catalyst inside of a microvial. Then derivatized sample injected in to the GC-MS. Derivatization reaction conditions were studied and optimized. Derivatization reaction was performed using 1.2 µL volume of triflouroacetic anhydride at 100 ? C during 20 min. Experimental parameter such as percentage of triflouroacetic anhydride in octanol, extraction time, extraction temperature, amount of salt and acid were studied and optimized. The best extraction efficiency was obtained using octanol including 10% triflouroacetic anhydride, 1.8 µL volume of organic solvent, stirring rate of 350 rpm, 20 min extraction time, 42 g/L Na 2 SO 4 and 7% of concentrated sulfuric acid in sample solution at room temperature. For this method, reproducibility ranging from 5.1 to 8.5% and the limits of detection (LODs) ranged between 0.1 and 1.2 µg/L were obtained. The proposed method was used for analysis of real sample such as drinking water, pool water, ground water and kashkan and zayanderood river water samples.