ABSTRACT. In this study, the raw oil products from a thermochemical conversion process of swine manure were characterized based on elemental composition, benzene solubles, heating value, and water content. The analytical results of 78 samples showed that the raw TCC oil products had an average elemental composition of 71.1% carbon, 8.97% hydrogen, 4.12% nitrogen, 0.2% sulfur, and 3.44% ash t is very important that biomass-derived oils are characterized in order to utilize them directly as fuel or for further upgrading. The chemical compositions of the biomass-derived oils are complicated and extensive numbers of compounds have been reported (Elliott et al., 1988;Pakdel and Roy, 1988;Piskorz et al., 1988;Maggi and Delmon, 1994;Sipila et al., 1998). The chemical and physical stability of the biomass-derived oils are also important for long-time storage (Adjaye et al., 1992). Rick and Vix (1991) proposed some requisite physical and chemical properties of biomass-derived oils for use as fuel in industrial plants, which included chemical composition, physical and thermal properties, viscosity, and the water content of the biomass-derived oils, and compared them with commercial fuel oils.The elemental compositions of biomass-derived oils vary widely because of the diverse sources of feedstock. Boyles (1984) Idaho, Moscow, composed of 58% carbon, 7.6% hydrogen, and 33.4 % oxygen. The heating value was 24 MJ/kg. According to the analyses of Piskorz et al. (1988), the composition of the oils obtained by fast pyrolysis of four different wood feedstocks was very similar, and contained about 54% carbon and 6.9% hydrogen. The water content of the pyrolytic liquids ranged from 18% to 20% by weight. Elliott et al. (1988) analyzed and compared the elemental compositions of several liquefaction oils from different high-moisture (90%-95%) biomass feedstocks. Their results showed that the process yields varied from 19.2% to 34.7% and the biomass-derived oils had a similar carbon and hydrogen content of 75% and 9%, respectively. Klass (1998) compared a few properties of liquid oils created by flash pyrolysis and by direct liquefaction of different biomass. His results showed that the carbon, hydrogen, and oxygen contents were about 53%, 6.2% and 40%, respectively, for flash pyrolysis oils, and about 79%, 8% and 14%, respectively, for direct liquefied oils. The oxygen content indicates a large difference in the energy content, or the heating values, of the oils, which were about 22 MJ/kg and 34 MJ/kg for flash pyrolysis and direct liquefied oils, respectively.Our previously reported research showed that oil products were produced by a thermochemical conversion process of swine manure and the process converted 62% or more of the volatile solids in the feedstock into a raw oil product (He et al., 2000a). The process parameters affecting the process, including the TCC operating temperature, retention time, initial process gas to feedstock volatile solids ratio, feedstock pH, feedstock total solids content, and different types of pro...