Abstarct: In this research, a rapid, simple and sensitive method for determination of Fluoride at trace levels is described. Zirconyl chloride reacts with Xylenol orange in hydrochloric acid media forming a red complex with 2:1 (M2L) stiochiometry which absorbs at 552nm. fluoride in two different ranges was determined through its catalytic effect . For the first range, Beer’s law is obeyed in the range of 5-40ppb. Detection limit is 3.5ppb and analytical sensitivity is 0.39 ppb with relative standard derivation of 2.22 percent. For the second range, Beer’s law is obeyed in the range of 1-4ppm. Detection limit is 0.56ppm and analytical sensitivity is 0.034 ppm with relative standard deviation of 1.04 percent. The effects of different interfering ions in determination of fluoride is investigated and methods for their eliminations is described. The proposed method was applied to determination of fluoride in real samples.