Model garbage was liquidized by a thermochemical process at 150-250degreesC and 3.5-7.0 MPa and by a mechanically disrupted process. The organic compositions of the liquidized model garbage, the mechanically disrupted garbage and their separated phases were analyzed. The liquidized garbage had a large amount of lower molecular weight organic acids compared with the mechanically disrupted garbage. On the other hand, it had a small total sugar amount, including simple sugars, oligosaccharides, polysaccharides, and their derivatives. The HPLC results also indicated that the amounts of fructose and glucose decreased during the liquidization. They were decomposed to other compounds, such as sugar derivatives and acids. Considering that low molecular weight organic acids can be easily decomposed by anaerobic digestion, these results show that the anaerobic digestion of the liquid phase could contribute to a higher digestion rate compared with that of the mechanically disrupted garbage.