Influence of steam-treatment upon properties, structure, and composition of red oak was investigated. Small specimens of red oak heartwood were submitted to steam-treatments at atmospheric pressure for 1.5, 3, 6, 12, 24, 48, and 96 hours. Short steaming induced little or no changes in the properties and the composition of red oak. Prolonged steaming, however, resulted in significant changes in physical and mechanical properties as well as in structure and chemical composition of wood. Shrinkage increased significantly with increasing steaming time. After 96 hrs of steaming volumetric shrinkage to the air-dry condition was 4.4 times that of the non-treated wood and was thus indicative of cell wall collapse. Specific gravity and equilibrium moisture content were decreasing and air-dry density was increasing with an increase in steaming time. Color of wood became darker and the fluid content brighter with prolonged steaming. / Ph. D.