Trichloroethylene (TCE) and tetrachloroethylene (PCE) are commonly found contaminants in soil and groundwater. However, the persulfate anion (S2O82-) is an oxidant; when activated with ferrous cation (Fe2+), it generates a stronger oxidant (known as a sulfate free radical, SO4-center dot), which may be used for the destruction of contaminants. Hydroxypropyl-beta-cyclodextrins (HP-beta-CDs) are environmentally benign glucose-based molecules that have the ability to increase the solubility of contaminants such as TCE and PCE and make them more amenable to degradation by chemical oxidation. The ultraviolet (UV) and hydrogen nuclear magnetic resonance (H-1 NMR) spectra of various inclusion complexes of HP-beta-CD, Fe2+ cations, and TCE showed that HP-beta-CD forms inclusion complexes with organics, Fe2+ cations, and combinations thereof. The apparent solubilities of TCE and PCE in aqueous solutions that contain HP-P-CD were observed to increase linearly with concentration. When persulfate was activated by the continuous addition of Fe 21 cations in a system where TCE and PCE were present as dense nonaqueous phase liquids (DNAPLs), the presence of HP-beta-CD increased the dissolved contaminant concentrations and the contaminants were attacked preferentially, most likely because of a controlled and slower rate of generation of the SO4-center dot species.