Last years hydrogen as energy carrier becomes one of the best solutions of energy and ecological problems. Intensive development of fuel cells, especially based on proton exchange membrane (PEM), where pure hydrogen is needed, stimulates electrolyzers development for the future application in hydrogen energy and technology. From point of view of the authors PEM electrolysis is very perspective for this goal. Advantages and possible fields of applications of this type of electrolyzers in comparison with another one are reviewed. Some results achieved up to now in PEM electrolysis, including last achievement of the authors, are summarized. (c) 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.