Abstract: The color reaction of mercury with p-Sulfobenzylidene rhodanine (SBDR)was studied.A stable complex was formed by reaction of SBDR with mercury ion (Hg²⁺)in a pH=4.0 acetic acid-sodium acetate buffer solution at the presence of tween-80.The complex was extracted by Waters Sep-Park-C₁₈ cartridge and eluted with ethanol. The absorption of the eluent was determined by spectrophotometry at 520nm of maximum wavelength.The molar absorptivity of this complex was about 1.21×10⁵ L·mol^-1·cm^-1.The relationship between the absorption of the eluent and its Hg²⁺ concentration observed the Beers law when the concentration of mercury ion was in the range of 0.01 to 1.50μg/ml.The contents of mercury in several tobacco leaves were determined.