Abstract: A simple and fast experimental method for estimating the Henry′s law constant (HLC) of a volatile organic compound (VOC) in water samples was developed; it required only the equilibrium liquid phase concentration of a close system partially filled with the VOC solution for calculating its HLC of the test conditions. The simple experimental method was highly reproducible; its relative standard derivations (RSDs) for 5 minor gasoline constituents (MTBE, benzene, toluene, ethyl benzene, oxylene) were less than 5%. Compared with the HENRYWIN calculations, the experimental HLCs of those VOCs, nitrobenzene, and trichloro ethylene (TCE) were all in better agreements with most experimental values reported in the two USEPA databases and the literature. The method was utilized for estimating HCL of different solution temperatures and composition. HLC of MTBE, benzene, toluene and TCE increased as the temperature went up and that they were higher in the bisolute solutions with greater effect noted due to presence of a more soluble coexisting VOC.