The main purpose of this study was to evaluate the cooling performances of two different types of cross flow indirect evaporative coolers (IECs) operated in two different operation modes: general and regenerative. The cooling performances of the IECs were tested in each operation mode in an environmental chamber. In the general mode, the secondary air stream passing through the wet channels was the return air from the conditioned zone; whereas, in the regenerative mode, a portion of the primary air leaving the dry channels was redirected to the secondary channels. The IEC performances were measured under constant primary air inlet temperature and humidity ratio with variations of the primary airflow. As indexes of the IEC performance, the wet-bulb effectiveness and cooling capacity of both IECs in each operation mode were estimated based on the measurement data. The experimental results revealed that, in the general operation mode, both IECs exhibited higher sensible cooling performances in terms of wet bulb effectiveness than in the regenerative mode in a 100% outdoor air system application. (C) 2017 Elsevier Ltd. All rights reserved.