An experimental investigation was carried out on an indirect evaporative cooling system, consisting of a porous ceramic and a heat pipe. The performance and characteristics were analysed for various operating conditions, including air humidity, temperature, velocity and solar irradiation effects. The results indicated that the cooling capacity increased as air humidity and solar irradiation decreased, or as air temperature and velocity increased. The results also showed that only the indirect evaporative cooling system has the ability to operate under high solar irradiation conditions. These experimental data will be useful for future design.