PCBs, DDT, dioxins, and other halogenated organic compounds have been detected in many of the nation's waterways at significantly elevated concentrations. It has been shown that the concentrations of PCBs in sediments have declined since their use has been discontinued; however, in recent years, the concentrations have remained essentially constant (above risk-based levels). Therefore, although use of many of these compounds has been discontinued, they are very persistent in the aquatic environment, and they are still present in the nation's sediments at concentrations that pose significant risk to the environment and to humans. These chemicals have a strong potential to bioaccumulate in aquatic organisms and to predatory species (including humans) who consume the aquatic organisms. Zero-valent metals (including iron) have been shown to be effective for dechlorinating contaminants such as trichloroethene, dichloroethene, trichloroethane, and PCBs in water. It has also been shown that palladization of the iron powder significantly enhances the dechlorination of solvents in water. However, little research has been done to test the use of zero-valent iron (or palladized iron) for remediation of sediments contaminated with chlorinated organic compounds. This study evaluated the use of zero-valent iron and palladized iron to dechlorinate PCBs in sediment. Natural sediments were spiked with 200 mg/kg of PCBs (2,2′,4,4′,6,6′- hexachlorobiphenyl). The spiked sediments were allowed to age for one month. After aging, the spiked sediments were treated with either iron powder or palladized iron powder. In addition, some of the samples were autoclaved prior to spiking to evaluate the effects of biological activity on the process. The samples were analyzed periodically using standard EPA extraction and analytical methods. Analyses were done using a gas chromatograph with electron capture detector. In addition, confirmation analyses were conducted using a gas chromatograph/mass spectroscope. Results of the study show that without treatment, the PCB concentrations remained nearly unchanged. Treatment with iron powder alone or with palladized iron powder may have reduced the PCB concentrations by 50% in 97 days. Copyright ASCE 2004.