A study was made of the functional characteristics of a rock bed regenerative indirect evaporative cooling system (RBR). The study was divided into two portions: The first dealing with the experimental investigation of the thermodynamic behavior of the system and the second with the development of a mathematical method of simulating its performance. Indirect evaporative cooling systems based on rock beds for heat exchange and/or storage are technically feasible for regions that do not require dehumidification of outdoor air for comfort. The mathematical model used for the simulation tracks the experimental data, thus providing the system designer with a valuable tool. The rock bed regenerative cooling system offers a viable alternative to the expensive air-conditioning unit and the comfort limited evaporative cooler for providing comfort conditions. It also offers an operating savings potential in both electrical demand and consumption and therefore a cost savings under current electrical rates and the proposednew demand rate charges.