This paper analyzes the operation of a grid-assisted wind power system dedicated to hydrogen production. Several operation modes are evaluated with the aim of establishing control strategies for different requirements such as optimum wind power capture, maximum H-2 production rate and maximum clean H-2 production. Each operation mode is achieved by specific control of the grid-side power electronic converter. The operation of the wind turbine, the electrolyzer and the electronic converter connected to a common DC-bus are represented on the same voltage-current plane. Basic schemes of controllers are suggested to fulfill operation requirements. Curves of power and H-2 production rate as function of wind speed are displayed for each mode. Also, conclusions about contribution of wind energy to clean H-2 are drawn. (C) 2010 Elsevier Ltd. All rights reserved.