This paper reports the comparative behavior of commercial pervaporation membranes in the recovery of acetic acid from acetylation industrial effluents. The main components of the industrial feed mixture are acetic acid and water; the initial content C-H2O = 24-26 wt %. The performances of four commercial membranes were investigated; the results indicate that all of the membranes were highly selective and permeable toward water. Both the selectivity and permeability were strongly feed-composition-dependent. The selectivity decreased and the permeability increased as the water concentration in the feed increased. Calculation of the pervaporation separation index (at 80 degreesC and 10 wt % water concentration) as the product of flux and the separation factor led to the selection of the Symplex membrane (GKSS) that behaved more successfully. Because the Symplex membrane is not commercially available on and industrial scale, the CMC-CF23 membrane from Celfa was selected in order to make detailed studies. After a careful experimental design, the flux rate of water permeation and the separation selectivity were determined in the range of temperature 50-80 degreesC and water content 1-25 wt %. Increased temperatures resulted in larger fluxes. For a fixed water concentration value in the feed of 10 wt %, the water flux through the CMC-CF23 membrane increased from 0.38 kg m(-2) h(-1) (50 degreesC) to 1.56 kg m(-2) h(-1) (80 degreesC). The results were satisfactorily predicted by a semiempirical model based on Fick's law with concentration-dependent diffusivity parameters.