The slow oxygen reduction reaction (ORR) kinetics on Pt catalysts is among the most limiting factors in the energy conversion efficiency of the state-of-the-art PEMFC. Also, Pt is scarcely available at a high price. Alternative materials are therefore highly sought for fuel cell applications. This review will concentrate on the electrochemical ORR on non-Pt catalysts, especially the experimental development during the past five years. Emphasis is placed on the understanding of the fundamental materials chemistry. This understanding seems pivotal for new designs of PEM cathode materials. Future outlooks are provided for researchers in engineering to select promising candidates for ORR. (c) 2005 Elsevier B.V. All rights reserved.