Methyl tert-butyl ether (MTBE)is used in gasoline (up to 15%) as an octane booster. Increase usage of MTBE coupled with high incidences of leaking underground storage tanks and recreational watercraft operation has led to MTBE contamination of surface waters, groundwater, soils, and sediments. The compound is extremely water soluble and moderately volatile; thus, it is highly mobile in both groundwater and surface waters. MTBE is a cancer suspect agent and there is substantial evidence that reformulated gasoline containing MTBE is hazardous to man and animals. Adverse health effects such as headaches, depression, bronchitis and sinus problems have been reported. Physicochemical treatment processes including ozone and perozone treatment, pump and treat by passage via activated carbon, air sparging, UV photolysis, adsorption to zeolites and sorption to high silica zeolites have been considered. Separation of volatile organic compounds (VOCs) from liquid streams by membrane air stipping (MAS) is being considered as an alternative that may help overcome some of the shortfalls of the conventional treatment methods. It is reported that MAS offers an order of magnitude higher overall volume specific mass transfer coefficient than that of packed-tower air stripping and needs much lower air-to-water ratio to achieve the same degree of removal due to its multi-pass nature. The benefits of lower air-to-water ratio facilitates the use of a closed-loop system to avoid transferring VOCs from aqueous to air phase, either by destroying or trapping the VOCs. This study presents the evaluation of a polypropylene hollow fiber membrane system to remove MTBE. The hydrophobicity of the fiber maintains adequate separation between aqueous and gaseous phases, permitting an efficient separation of volatile and semivolatile compounds from water to gas. The hollow nature of the fiber and its high porosity permit high rates of mass transfer across the membrane. We evaluate the removal efficiency of MTBE from water using a commercial HFM module and get the overall volume specific mass transfer coefficient by regression analysis. MTBE removal is a strong function of membrane length, aqueous flowrate and temperature, and gaseous flowrate and relative pressure.