In this study a desalination system based on air humidification-dehumidification is investigated theoretically and experimentally. To evaluate the productivity of the proposed humidification-dehumidification desalination unit, a mathematical model has been developed for the design of a unit, based on mass and energy balances as well as thermodynamic analysis of cooling tower and condenser. The results obtained from the theoretical model are in very good agreement with those obtained experimentally. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.