The objective of this paper is to design, analyze and evaluate a controller for the water level of U-tube steam generators. The control objective is to closely regulate the water level during extreme load variations and despite drifts in process parameters. The controller design is based on the H ∞-norm. Gain-scheduling is used to obtain a global water-level controller. The controller performance is satisfactory at all power levels. In view of a comparative analysis of the H ∞ controller with an LQG/LTR controller, implementation and use of the gain-scheduled H ∞ controller over the equivalent LQG/LTR controller is recommended.