Mass transfer of lactic acid was investigated during its extractive recovery from fermentation broths in a hydrophobic hollow-fibre membrane module. The solvent and the aqueous phases were continuously recycled through the hollow-fibre module into their respective reservoirs, and the mass transfer rate was calculated from the measurements of concentration of lactic acid in solvent phase. Mainly, the tubeside resistance controlled the mass transfer rate. A mathematical analysis was conducted for the mass transfer process in the membrane module and values of the overall mass transfer coefficient were estimated at different flow rates.