Acetone-butanol-ethanol (ABE) fermentation is a process that uses bacterial Fermentation to produce acetone, n-Butanol, and ethanol from starch. It was the primary process used to make acetone during World War I, such as to produce cordite. The process is anaerobic (done in the absence of oxygen), similar to how yeast ferments sugars to produce ethanol for wine, beer, or fuel. The process produces these solvents in a ratio of 3-6-1, or 3 parts acetone, 6 parts butanol and 1 part ethanol. It usually uses a strain of bacteria from the Clostridia Class (Clostridium Family). Clostridium acetobutylicum is the most well-known strain, although Clostridium beijerinckii has also been used for this process with good results.

The production of butanol by biological means was first performed by Louis Pasteur in 1861. In 1905, Schardinger found that acetone could similarly be produced. Fernbach's work of 1911 involved the use of potato starch as a feedstock in the production of butanol. Industrial exploitation of ABE fermentation started in 1916 with Chaim Weizmann's isolation of Clostridium acetobutylicum, as described in U.S. patent 1315585.

In order to make ABE fermentation profitable, many in-situ product recovery systems have been developed. These include gas stripping, pervaporation, membrane extraction, adsorption, and reverse osmosis. However, at this time none of them have been implemented at an industrial scale.

For gas stripping, the most common gases used are the off-gases from the fermentation itself, a mix of carbon dioxide and hydrogen gas.

ABE fermentation, however, is not profitable when compared to the production of these solvents from petroleum. As such there are no currently operating ABE plants. During the 1950s and 1960s, ABE fermentation was replaced by petroleum chemical plants. Due to different raw materials costs, ABE Fermentation was viable in South Africa until the early 1980s, with the last plant closing in 1983.