Spirogyra gratiana transeau alga was liquefied in organic solvents with and without catalyst in a cylindrical reactor at temperatures of 493, 513, and 533 K under supercritical conditions. The liquefied compounds were extracted with diethyl ether and benzene using an extraction procedure. The product yields in supercritical methanol, ethanol, and acetone were found to be 15.5, 23.7, and 34.4% at 533 K, respectively. The highest conversion to liquid products was obtained in supercritical ethanol with 10% sodium hydroxide as catalyst at the same temperature in the catalytic runs. Main chemical compounds present in the liquid product obtained in acetone without catalyst at 533 K were analyzed and characterized by gas chromatography-mass spectrometry (GC-MS).