The chemical and physical composition of the catalysts used in fuel cells are determined by the type of cell for which they are intended and its operating conditions. The six types of fuel cell presently in use or under development are described in the context of their electrocatalyst requirements. The important features of the current-voltage characteristics of fuel cells and the extent to which these depend upon the electrocatalysts and electrode structures are described. The limitations of electrocatalysts presently used in fuel cell developments and opportunities for improving their performance are discussed and analysed. Following this overview of electrocatalyst developments for fuel cells, the paper concludes with details of the development of precious metal based electrocatalysts for proton exchange, solid polymer fuel cells.