Buildings that use radiant slab systems with evaporative cooling sources have shown to be energy efficient. However, control of the systems is challenging because of the slow response of the slab and the limited capacity of cooling sources. The objectives of this paper are to: (1) create a simplified dynamic model of radiant slab system for implementation in real-time model predictive controller (MPC); and (2) test the MPC energy and thermal comfort performance in a case study building. A calibrated EnergyPlus model of the building was developed as the testbed. The MPC is compared with the existing rule-based control method for a cooling season in a dry and hot climate. The results indicated that the MPC controller was able to maintain zone operative temperatures at EN 15251 Category II level more than 95% of the occupied hours for all zones, while with the rule-based method, only the core zone were maintained at this thermal comfort level. Compared to the rule-based method, MPC reduced the cooling tower energy consumption by 55% and pumping power consumption by 25%. (C) 2014 Elsevier B.V. All rights reserved.