This paper concerns the control of an autonomous hydrogen production system basically consisting in a solar panel array supplying an alkaline electrolyzer, Following the current tendency of eliminating component duplication, these devices are not connected-with dedicated power electronics-to a common DC bus, but directly through a single DC-DC converter. This converter is aimed at adjusting the output voltages of the solar array and electrolyzer in order to maximize hydrogen production. To this end, a controller is proposed that meets the maximum power capture objective for the solar array and the power constraints of the electrolyzer. The controller is designed using concepts of hybrid control theory, which is very powerful to cope with the nonlinear and hybrid dynamics inherent to the system behavior. This hybrid approach provides simple design tools and allows a straightforward analysis of global stability properties. (C) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.