Scrap tires are a growing environmental problem because they are not biodegradable. In this investigation, supercritical extraction of scrap tire and co-processing of coal with tire oil were studied. In the first stage, tires were extracted at 400degreesC with a number of different solvents. The effects of the hydrocarbon and polar solvents used under the supercritical extraction conditions on the conversion and oil product of tire were determined, and it was observed that all volatile organic material of the scrap tire was converted to the liquid or gas product. In the second stage, coal and supercritical extracted tire oil (SCETO) samples were extracted with different solvents using various tire oil/coal ratios. In general, the use of tire oil generated an improvement for coal conversion. Further, the oil yield was higher than those of coal alone runs. The SCETOs were characterized using spectroscopic (FTIR) and chromatographic analytical techniques (GC-MS). GC-MS, and FTIR results showed that the oils are mainly comprised of alkyl aromatic species. A significant amount of alkyl-substituted phenol compounds was also found to be present in the oils. (C) 2003 Elsevier B.V. All rights reserved.