The membrane electrode assembly (MEA) is well known to be the critical component of a proton exchange membrane fuel cell (PEMFC). The interface between the membrane and the electrodes plays a significant role in controlling overall performance and durability. Moreover, the processing parameters to produce MEA have a major influence on the interface and allow novel materials to be evaluated in high performance fuel cell devices. In this paper. several parameters influencing processing conditions for MEAs with membranes based on novel wholly aromatic polymers were investigated and optimized Processing parameters are suggested. This paper demonstrates that the Water content present in the copolymers during MEA fabrication significantly influences the nature of the interface and, consequently, fuel cell performance. The optimized fabrication temperature reflects viscoelastic behavior and appears to be close to the hydrated glass transition or alpha relaxation temperature of the copolymer. It is Suggested to be a function of both water content, which can plasticize and reduce T-g, and molecular weight of the copolymer. (C) 2009 Elsevier B.V. All rights reserved.