A complete set of temperature-dependent physical-chemical property data (aqueous solubility (S W), octanol−water partition coefficient (K OW), vapor pressure (P), Henry's law constant (H), octanol−air partition coefficient (K OA), and octanol solubility (S O)) for α-, β-, and γ-hexachlorocyclohexane (HCH) is derived by evaluating, averaging, and regressing all experimentally obtained values reported in the literature. Properties for each isomer are adjusted slightly to ensure thermodynamic consistency. That adjustment is sized according to, and is smaller than, the uncertainty apparent from the range of reported experimental values. The data analysis confirms that an unsually high K OA and an unusually low H reported for β-HCH are in agreement with the measured S W and P values when these are converted to the liquid state. Linear solvation energy relationships fail to predict the observed differences in the partitioning behaviors of the three isomers.