This paper discusses membrane biotreatment of air laden with volatile organic compounds (VOC). Microporous flat-sheet and hollow-fiber membrane contactors were used to support air-liquid and liquid-liquid mass transfer interfaces. These modules were used in a two-step process to transfer VOCs from a contaminated air stream, through a stripping fluid, to a degradative biofilm, where the compounds were effectively mineralized. The membrane contained in the module was coated on the air-contacting side with either perfluorodimethyldioxole/ tetrafluoroethylene or plasma-polymerized silicone rubber. Contact times of the VOC-laden air with the membranes varied between 0.1 to 0.4 sec. VOC removal efficiencies ranged from 44 to 97%, depending on the air contact time. Octanol was used as the stripping fluid because of its low vapor pressure and water solubility, the high partitioning of VOCs into octanol in air, and its ability to inhibit bacterial growth. The concentration of VOC in octanol was found to affect the removal efficiency and transfer rate of VOCs into and out of the stripping fluid. Furthermore, extraction of specific compounds from the air stream into octanol was observed to unaffected by the presence or concentration of other VOCs in the air stream.