The device described in this paper is a flat sheet membrane module that removes humidity from the space suit breathing loop by venting it to the vacuum of space. The module consists of alternating vacuum layer assemblies and vent layer assemblies separated by solid polymer membrane sheets. The module is designed to optimize volume and pressure drop at a given vent flow rate and water removal rate. Both Hamilton Standard and the NASA Johnson Space Center tested the module under varying EMU flow and humidity conditions; the results of the testing are presented in the paper. The module met or exceeded all of the design goals set forth in the program statement of work, including volume, pressure drop and water removal rate.