A series of field tests of hybrid desiccant cooling systems was conducted during July and August 2012. The temperature and humidity of supply and return air and power and heat consumption were monitored, and data were transferred in real time through the internet. The performance of the cooling system (i.e., cooling capacity and the coefficient of performance [COP]) was evaluated from measured data and variations with regard to outdoor conditions were analyzed. The cooling capacity decreased with an increase of outdoor temperature, while it increased as outdoor humidity increased. The COP also increased with an increase in outdoor humidity. However, the dependence of the COP on outdoor temperature was rather weak.