In the present paper the steam cycle proposed by Spazzafumo has been again taken into consideration and the effectof the flow variation on the cycle performances has been investigated. The isothermal expansion with increasingflow causes a decrease in cycle efficiency due to the greater condenser losses and, at high superheated temperatures,to the impossibility of full recovering of the available heat at the end of the expansion. However, using part of thisheat for preheating the required hydrogen and oxygen, yields a significant increase in efficiency. (C) 1999International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.