One of the major purposes of using chemical protective membranes is to minimize the exposure of wearers to hazardous chemical warfare agents (CWAs) such as nerve agents and mustard gas However, many chemical protection membranes have limitations such as low breathability, which can cause discomfort. and poor mechanical stability Polystyrene sulfonic acid (PSS) was investigated for chemical protection due to its ability to hinder the permeation of organic agents while allowing water vapor to pass through Cross-linked PSS was filled into the open pores of polypropylene nonwoven membrane supports, and the resultant PSS-filled nonwoven composite membranes have Improved mechanical properties and reduced vapor permeation for simulants of sarin, soman, VX, and mustard gas At the same time, these PSS-filled nonwoven membranes retain high water vapor permeation that is beneficial for reducing heat exhaustion. PSS-filled nonwoven membranes were also hot-pressed to further reduce the membrane thickness and vapor permeation, and to Improve the mechanical properties. Results show that hot-pressed PSS-filled nonwoven membranes are mechanically strong and have lower CWA simulant vapor permeation and higher water vs CWA simulant selectivity than commercially available Nafion (R). Therefore, PSS-filled nonwoven membranes are promising candidate materials for chemical vapor protective applications (C) 2010 Elsevier B.V All rights reserved.