Inexpensive household steel wool was used as a reducing agent for the reductive dechlorination of polychlorinated biphenyls (PCBs) in supercritical carbon dioxide (scCO(2)). Untreated steel wool does not produce significant results. Steel wool treated with 6 N HCl, however, showed complete reduction of the PCBs (Aroclor 1254) used. Scanning electron microscopy (SEM) reveals the formation of nanoscale pits (nanopits) on the surface of steel wool after etching with HCl. These nanopits are responsible for the high efficiency of the hydrodechlorination process,