Coal liquefaction residue (CLR) was produced in about 30% yield through the process supporting unit (PSU) of the NEDOL coal liquefaction process. Therefore, the investigation about the reaction conditions on the upgrading of CLR is required. In this study, the effects of the oxidation pretreatment of CLR with H2O2 on the subsequent hydrogenolysis reactivity of CLR were investigated. On the pretreatment of CLR at 50 degreesC for 6 h, iron (II) sulfate, which was oxidized from pyrrhotite in CLR during storage and the pretreatment, acted as the Fenton's reagent with H2O2. The oxidation of polycyclic aromatic clusters in CLR occurred by the hydroxyl radical generated from H2O2 with ferrous ion in mineral of CLR. On the hydrogenolysis reaction of the pretreated CLR, the upgrading of CLR, such as the increase of n-hexane soluble yield and the decrease of n-hexane insoluble but acetone soluble yield, was observed in comparison with that of untreated CLR. (C) 2002 Elsevier Science B.V. All rights reserved.