Quantitative structure-property relationship (QSPR) models have been developed which accurately calculate the congener-specific aqueous solubilities (S) and Henry's Law constants (HLCs) of polychlorinated biphenyls (PCBs). QSPRs were generated based on molecular models which were sensitive to slight changes in chemical structure. PCB aqueous solubilities were found to be a function of total surface area, melting point, and third shadow area. Observed HLCs were a function of the second moment of inertia, path-four connectivity index, path-three K index, and the second and third principal polarizabilities.