BACKGROUND: Reactive liquid-liquid extraction is a promising technique for the direct recovery of carboxylic acids from bioconversion media. This work focused on the optimization of 3-hydroxypropionic acid (3-HP) reactive extraction assisted by hollow-fiber membrane contactor (HFMC), using tri-n-octylamine (TOA) and Aliquat 336 as extractants in n-decanol, and on its practical application for the recovery of 3-HP obtained from glycerol bioconversion by Lactobacillus reuteri. RESULTS: The results underlined the influence of the initial pH and 3-HP concentration of the aqueous medium and the impact of extractant phase composition on the extraction performances. The highest distribution coefficient of 3-HP (K-D = 13.0) was observed at pH = 3 with 10% v/v TOA mixed with 10% v/v Aliquat 336 in n-decanol. This study showed that the acid concentration and the ratio of amines used between TOA and Aliquat 336 in n-decanol did not have a great impact on the K-D during 3-HP reactive extraction, whereas it had an influence on the extraction kinetics. Moreover, 3-HP reactive extraction assisted by HFMC from real bioconversion broth with glycerol as the substrate was shown to be feasible, with the same order of magnitude of extraction kinetics but with a lower K-D compared with reactive extraction using model broth. CONCLUSIONS: 3-HP was predominantly extracted from the bioconversion broth, confirming the high selectivity of the extraction process studied and the high potential of this approach applied to the biotechnological production of 3-HP. (C) 2016 Society of Chemical Industry