A study has been made of the electrochemical reduction of pentachlorophenol (PCP) on a lead electrode in both water and propylene carbonate. A combination of voltammetric measurements and analysis of reaction products by high performance liquid chromatography (HPLC) have established that the reduction of PCP in propylene carbonate occurs by two different pathways, depending upon the electrode potential. At -1.9V vs SCE, reduction is mediated by adsorbed hydrogen, whereas at -2.3V vs SCE direct reduction of PCP also occurs. A similar approach has established that the reduction of PCP in water follows only one reaction pathway, namely, direct electron transfer from lead to PCP.