This paper presents the application of a Model Predictive Controller to the temperature control in a solar air conditioning plant. The controller uses a Smith Predictor and includes a feed-forward control action to reject disturbances caused by solar radiation and the auxiliary gas heater. The tuning procedure is simple and allows a good compromise between robustness and performance. The behaviour of the controller is illustrated by experimental results. (C) 2004 Elsevier Ltd. All rights reserved.