In this work, a membrane cross flow filtration is studied specifically for the purpose of air dehumidification. A flat sheet composite membrane comprising ceramic and polymeric layers with varied water vapor permeability and selectivity has been developed. Effects of the feed air velocity and humidity, the membrane permeability and selectivity, and the permeate pressure on dehumidification performance (i.e. water vapor removal) and resulting COP (Coefficient of Performance) under a cross-flow flat-sheet setting is systematically studied. Results have shown that the membrane dehumidification performance does not depend on the feed air humidity while its COP does not dependent on the membrane's permeability and the feed air velocity. There exists a tradeoff between the membrane's ability to dehumidify and its achievable COP when both selectivity and permeate pressure are varied. (c) 2015 Elsevier B.V. All rights reserved.