This article describes three different techniques for the determinatio
n of the current density distribution in operating fuel cells and comp
ares their relative benefits with respect to ease of implementation an
d information gain. Real-time current density distribution data under
steady state as well as transient conditions are presented and it is s
hown that they can contribute to an improved understanding of water ma
nagement and reactant distribution over the active fuel cell area. The
importance of these factors for the optimisation of fuel cell perform
ance is discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.