In this study, black alder (Alnus glutinosa L.) wood samples were subjected to supercritical fluid extraction (SFE) using acetone, methanol, and water as solvent. The highest yield (62.4%) of SFE was obtained from black alder with water solvent at 678 K. The supercritical fluid extracts were fractionated into water soluble, acetone soluble, phenolic, fatty acid, polar, and nonpolar fractions. The lowest and highest yields of phenolic fractions from the supercritical water extraction runs were 5.3% and 15.4%. The lowest and highest yields of polar fractions from the supercritical water extraction runs were 14.6% and 16.7%. Increases of higher heating values (HHVs) in the supercritical fluid extracts are range from 48.1% to 71.4%, from 41.7% to 67.2%, and from 34.4% to 61.9% for acetone, methanol, and water, respectively. Carbon and hydrogen contents in supercritical fluid extracts are higher than those of in the original black alder sample.