NOVELTY - Recovering a volatile carboxylic acid from an aqueous stream comprises: evaporating the aqueous stream to produce a vapor stream comprising the vaporized carboxylic acid and water vapor, which aqueous stream is produced by a conversion process using lignocellulosic feedstock as substrate; contacting the vapor stream with organic solvent to extract the volatile carboxylic acid, thus producing a liquid stream comprising the organic solvent and the volatile carboxylic acid, and a water vapor stream; and separating the volatile carboxylic acid from the organic solvent.    USE - The method is useful for recovering a volatile carboxylic acid (including acetic acid) from an aqueous stream (claimed).    ADVANTAGE - The process is efficient and economical for recovering volatile carboxylic acids.    DETAILED DESCRIPTION - Recovering a volatile carboxylic acid from an aqueous stream comprises: evaporating the aqueous stream to produce a vapor stream comprising the volatile carboxylic acid that has been vaporized and water vapor, which aqueous stream is produced by a conversion process using a lignocellulosic feedstock as a substrate; contacting the vapor stream with an organic solvent so as to extract the volatile carboxylic acid present in the vapor stream, thus producing a liquid stream comprising the organic solvent and the volatile carboxylic acid, and a water vapor stream, where the organic solvent has an atmospheric boiling point of at least 150 degrees C and is insoluble in water; and separating the volatile carboxylic acid from the organic solvent. An INDEPENDENT CLAIM is also included for a process for recovering a volatile carboxylic acid from an aqueous stream comprising: evaporating the aqueous stream to produce a vapor stream comprising the volatile carboxylic acid that has been vaporized and water vapor, which aqueous stream is produced by a conversion process that comprises pretreating a lignocellulosic feedstock with acid or alkali to produce a pretreated feedstock composition comprising fiber solids containing cellulose, hydrolyzing the cellulose to glucose with cellulase enzymes and beta -glucosidase and fermenting the glucose to ethanol (preferred) or butanol; contacting the vapor stream with an organic solvent to extract the volatile carboxylic acid present in the vapor stream, thus producing a liquid stream comprising the organic solvent and the volatile carboxylic acid, and a water vapor stream, where the organic solvent has an atmospheric boiling point of at least 150 degrees C and is insoluble in water; and separating the volatile carboxylic acid from the organic solvent.