An experimental rig of two-stage evaporative cooling unit is constructed and tested in the Kuwait environment. The system is formed of an indirect evaporative cooling unit (IEC) followed by a direct evaporative cooling unit (DEC). The system is operated during the summer season of Kuwait with dry bulb temperatures higher than 45 degreesC. The system is operated as a function of the packing thickness and water flow rate of the DEC unit. Other parameters include the water flow rate to the IEC unit and the mode for operating the IEC heat exchangers. Results show that the efficiency of the IEC/DEC varies over a range of 90-120%. Similarly, the efficiency of the IEC unit is varied over a range of 20-40%. The efficiency of the DEC unit varies over a range of 63-93%. The data is used to correlate the Nusselt number for the air stream outside the IEC heatexchange unit. Results show that the Nusselt number varies over a range of 150-450, which corresponds to a heat transfer coefficient of 0.1-0.4 kW/m(2) K. These results are consistent with literature data and should be of great value in designing of IEC units. In summary, the results and analysis presented here indicate the attractiveness of the EC systems for indoor air conditioning. High efficiency is obtained irrespective of the high intake air temperature. It is highly recommended to continue research investigations in this area in search for low energy consumption air conditioning units as these would contribute to a cleaner environment and would conserve the limited resources of fossil fuel. (C) 2004 Published by Elsevier B.V.