In this work, microporous Engelhard titanosilicate-4 (ETS-4) incorporated thin film nanocomposite (TFN) membranes for water vapor separation were fabricated via interfacial polymerization. ETS-4 particles were synthesized and ground by an attrition mill to reduce particle size. The ground ETS-4 nanoparticles were well dispersed in 3,5-diaminobenzoic acid (DABA) solution followed by reacting with trimesoyl chloride (TMC) to get embedded in the polyamide selective layer on the outer surface of polysulfone (PSI) hollow fibers. The intrinsic properties of ETS-4 as well as TFN membranes were investigated by field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), atomic force microscopy (AFM) and water contact angle (WCA). The effect of ETS-4 concentration on water vapor permeance and selectivity was investigated. Increase in ETS-4 concentration during interfacial polymerization causes significant increase in selectivity due to its molecular sieving effect by sacrificing little permeance till 0.5 wt%, above which the selectivity deteriorates due to the agglomeration of ETS-4 nanoparticles. The maximum selectivity of 346 was obtained with 1377 GPU in permeance for the TFN membrane (DTE-0.5) with ETS-4 concentration of 0.5 wt%. Additionally, the effect of concentration polarization was examined and individual resistances from the overall resistance were calculated.