Separation of 2,3-butanediol from the complex fermentation broths is a difficult task and becomes a bottleneck in industrial production. Aqueous two-phase systems composed of hydrophilic solvents and inorganic salts could be used to extract 2,3-butanediol from fermentation broths. Aqueous two-phase extraction of 2,3-butanediol from fermentation broths was studied by ethanol and dipotassium hydrogen phosphate system. The influences of phase composition on partition of 2,3-butanediol, removal of cells and biomacromolecules were investigated. The partition coefficient and recovery of 2,3-butanediol reached up to 28.34 and 98.13%, respectively, and the selective coefficient of 2,3-butanediol to glucose was 615.87 when the system was composed of 24% (w/w) ethanol and 25% (w/w) dipotassium hydrogen phosphate. Simultaneously, cells and proteins could be removed from the fermentation broths and the removal ratio reached 99.63 and 85.9%, respectively. This process is convenient and economic, furthermore, the operation is easy to scale-up, that is, this method provides a new possibility for the separation and refining of 2,3-butanediol. (C) 2008 Elsevier Ltd. All rights reserved.