The aim of this study was the characterization of the extracellular polysaccharide (gum) from freshwater microalgae Chlorella sp. For this purpose, determination of the component monosaccharides and minerals were chosen as the structural properties, while the thickening effect on aqueous systems and the effect on the dispersed phase volume fraction of oil in water (o/w) emulsions were selected as the functional properties. The gum was found to contain the monosaccharides: glucuronic acid (385 g/kg); arabinose (325 g/kg); glucose (193 g/kg); fucose [alpha- and beta-anomers (31 g/kg and 14 g/kg, respectively)]; and the minerals: calcium (16.3 g/kg); sodium (7.7 g/kg); potassium (20.4 g/kg); and zinc (1.1 g/kg) reported on a dry weight basis. The gum from Chlorella sp. was found to be a potential thickening agent. Its thickening and secondary emulsifying effects were found to be compatible with most of the food-grade salts when these salts are used in the recommended range (1 to 30 g/L) for foods. It was found that its thickening and secondary emulsifying effects are confined to the acidic range (pH 4 to 6).