Abstract: Traces of molybdenum(Ⅵ) in water was reacted with 1.0 mL of 1.0×10-3mol·L-1 phenylfluorone (PF) solution in 4.0×10-3mol·L-1 HCl solution in the presence of 0.1 g of Triton X-114 per 10 mL of reaction solution.Cloud point extraction was applied to the reaction mixture by heating for 25 min at 75 ℃ in water bath,and centrifuging for 2 min to separate the phases.The upper aqueous phase was removed,and the absorbance of the Mo(Ⅵ)-PF complex in the lower micellar phase (after adding 0.4 mL of 0.02 mol·L-1 HCl and diluting quantitatively to 2.0 mL) was measured at the wavelength of its absorption maxium (523 nm) with reference to reagent blank.Range of linearity was kept between 20 and 140 μg·L-1 of Mo(Ⅵ),with detection limit (3S/N) of 12 μg·L-1.