Pentachlorophenol (PCP) was degraded in an aqueous mixture of tetrakis(sulfonatophenyl)porphyrin (TPPS) and Fe(II) at pH 6. The degradation was enhanced by the addition of ascorbic acid (ASC), and PCP was largely degraded to tetrachlorohydroquinone (TeCHQ) and tetrachlorocatechol (TeCC). Chloride ions were released during the reaction in molar amounts that were approximately 2-3 times larger than those of PCP degraded. This suggests that further oxidative products are also produced. The percentage of PCP degraded decreased with increasing concentrations of 2-propanol, a hydroxyl radical (OH.) scavenger. This supports the hypothesis that HO. is involved in PCP degradation. When an aqueous solution, which contained only TPPS, was shaken under aerobic conditions, H2O2 was generated at mM level after a 24 h reaction period. Thus, TPPS appears to be involved in the reduction of dissolved oxygen to O-2(.-), leading to the generation of H2O2. However, in the presence of both TPPS and ASC, >100 muM-levels of H2O2 were generated. This shows that the addition of ASC to TPPS enhances the generation of H2O2. These results lead to the conclusion that the degradation of PCP in the present systems can be attributed to a Fenton-like process. (C) 2002 Elsevier Science B.V All rights reserved.