A metal hydride based solar water pump has been simulated and effects of various design and operating parameters have been studied. The study shows that if the cost of metal hydride is much higher than the collector and/or land cost, then one should use more number of thin hydride bed solar collectors for best performance. On the other hand, if the solar collector and/or land cost is much higher than hydride material cost then thick bed solar collectors are preferred. It is possible to optimize the system performance for different discharge heads by varying the enthalpy of formation of metal hydrides, which is a unique characteristic of the hydride based solar water pump. The study shows that depending on the design and operating conditions, it is possible to pump as much as 3000 1 of water in a day over a height of 15 m using 1-m(2) collector area. The maximum overall thermal efficiency of the metal hydride based solar water pump was found to be about 1.5%. (C) 2003 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.