The coliquefaction of Yallourn coal (YL) with polyethylene (PE) was carried out at 400 or 425 degrees C under pressurized H-2 in 1-methylnaphthalene or tetralin. In the coliquefaction without a catalyst, the conversion and the oil yield increased by 11-12% as compared to that of expected value from the additive values of respective runs. We considered that free radicals produced from YL coal were stabilized by the hydrogen abstraction from PE during the coliquefaction, and as a result beta-scission of PE markedly proceeded. The addition of a large amount of Fe(CO)(5)-S catalyst (Fe = 1.0 mmol, 2.79 wt %, S/Fe = 2) increased the conversion and the hexane soluble oil yield in the homoliquefaction of YL coal or PE, except for the conversion of PE in the reaction with TL. However, this catalyst did not promote the conversion and the hexane-soluble oil yield in the coliquefaction of YL coal with PE. When the amount of the iron catalyst was decreased to 0.4 mmol (1.12 wt %) against the same amount of coal and PE, the conversion and the oil yield in the coliquefaction run increased as compared to the reaction without or with the large amount of catalyst (Fe = 1.0 mmol). Since the excess amount of the catalyst rapidly provided hydrogen from the gas phase to YL coal-derived free radicals, hydrogen transfer from PE to YL coal decreased greatly.