The theory of sliding mode control is applied to a solar power plant described by a system of hyperbolic partial differential equations. The method of characteristics is used to extend the sliding mode concepts for application to partial differential equations. The main purpose of the controller is to manipulate the oil flow rate to maintain the field outlet temperature around the desired reference value, and, at the same time, to attenuate the disturbances effects. Through simulations themethod is shown to be effective in controlling a solar power plant under real disturbances data.