Cellobiose is a disaccharide with the formula (C6H7(OH)4O)2O. It is classified as a reducing sugar - any sugar that possesses the ability or function of a reducing agent. The chemical structure of cellobiose is derived from the condensation of a pair of β-glucose molecules forming a β(1→4) bond. It can be hydrolyzed to glucose enzymatically or with acid. Cellobiose has eight free alcohol (OH) groups, one acetal linkage, and one hemiacetal linkage, which give rise to strong inter- and intramolecular hydrogen bonds. It is a white solid.
It can be obtained by enzymatic or acidic hydrolysis of cellulose and cellulose-rich materials such as cotton, jute, or paper.<ref>Template:Cite journal</ref> Cellobiose can be used as an indicator carbohydrate for Crohn's disease and malabsorption syndrome.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Treatment of cellulose with acetic anhydride and sulfuric acid gives cellobiose acetoacetate, of which there is no longer a hydrogen bond donor (though it is still a hydrogen bond acceptor) and possesses aspects of being soluble in nonpolar organic solvents.<ref>Template:Cite journal and Template:Cite journal</ref>