A study of the reaction involving the heating of air dried and ground lignocellulosic materials such as wheat straw, corn stover, tobacco stalk, tobacco leave and hazel nut shell suspended in water containing sodium carbonate catalyst at elevated temperatures and pressures in a 0.1 liter autoclave. They have been converted to acetone-soluble oil and water-soluble chemicals by being heated for 75 minutes. Within the ranges of the reaction parameters studied: amount of the catalyst (2.0-11.0 wt %), water-to-solid ratio (1:1-5:1) and temperature (518-573 K). Nominal reaction time was 75 min and particle size was 0.6 mm. The optimum ratio of water to solid was found 3:1. The yield of total acetone-solubles were about 50 % of dry and ashless tobacco stalk in the presence of 11 % catalyst of used sample.