The use of indirect evaporative cooling technologies is an effective way to reach high energy efficiency systems and to reduce primary energy consumption. At present, interest in such systems is strongly increasing, with particular attention to data centers facilities. In fact, in these applications the indoor air temperature can be higher than the one of residential and commercial buildings, leading to a greater number of yearly operating hours of the system. In this paper an indirect evaporative cooler, based on a cross flow heat exchanger, has been tested and modelled. Many experiments have been carried out in typical data centers operating conditions, varying both water flow rate and inlet air conditions. A phenomenological model of the indirect evaporative cooler has been developed: the model takes into account the effects of the adiabatic cooling of the secondary air stream in the inlet plenum and the actual wettability of the heat exchanger surface. The model has been extensively validated and it is shown that simulation results are in very good agreement with experimental data. Therefore, it can be a suitable tool to design and to predict performance of indirect evaporative cooling systems. (C) 2017 Elsevier B.V. All rights reserved.