Solid oxide fuel cells (SOFC) are promising devices for high efficiency cogeneration. The most widely used and studied ones have an anion conducting electrolyte that requires high operating temperatures to limit ohmic losses across this electrolyte; temperatures typically range between 800 and 1,000 A degrees C. This temperature is associated with undesirable phenomena such as material interaction and insulating phase formation that result in unsatisfactory durability and high cost for market entry. Proton conducting solid oxide fuel cells (PCFC) constitutes a promising alternative since they allow a significant decrease in operating temperature. The Ba(Zr,Ce,Ln)O3-delta perovskite family exhibits ionic conductivities reaching 10(-2) to 10(-1) S cm(-1) at temperatures as low as 600-700 A degrees C, these values being obtained with anion conducting SOFC between 700 and 1,000 A degrees C. On the basis of a review of work on half cells and complete cells, this paper addresses the main parameters that control and limit PCFC behaviour. This analysis aims at proposing recommendations for designing and testing proton conducting fuel cells.