Swelling of a Nation film makes it very difficult to deposit thin catalyst layers on a membrane electrolyte. In this study, a process has been developed that utilizes the expansion of Nation film in the deposition so as to mitigate this problem. When the film is fully expanded, catalyst ink can be applied on to the membrane directly by means of spraying or blade pasting without concerns over swelling. The resulting membrane electrode assembly shows good performance relative to commercial products. (C) 2003 Elsevier Science B.V. All rights reserved.