Air conditioning is one of the essential requirements for households as well as work stations. Dehumidification in air conditioning is the highest energy-consuming component, where membranes could play a crucial role. In this work, we propose the coating of NEXARTM, a commercial pentablock copolymer in tetrahydrofuran on polyetherimide hollow fiber support for separation of water vapor from humidified air. The block copolymer in tetrahydrofuran forms a lamellar/parallel cylindrical structure separated by equidistance during the morphological transformation process giving its unique characteristics with higher water vapor transfer efficiency. Both vacuum and sweep gas modes of membrane dehumidification strategies are investigated along with the detailed study of the morphological transformation process under a controlled environment, which is supported by comprehensive scanning electron microscopic and atomic force microscopic imaging. The membrane has shown water vapor permeance up to 9089 GPU with water vapor to nitrogen selectivity up to 3870. The membrane can reduce the relative humidity from 80% to 41% proving one of the competitive materials for membrane dehumidification.