The traditional way to dehumidify the outdoor air in an A/C-system is by cooling the air downbelow the dew point temperature. For this process a refrigeration system is necessary torealise these low temperatures. Nowadays the disadvantages of refrigeration systems fordehumidification are widely known. An alternative method to dehumidify the air is byseparating the process of dehumidification and cooling.The paper will present a testing plant of 1200 m air/h which is installed in the University ofEssen. This A/C-systems works with liquid desiccants. The cooling of the process is doneonly by means of evaporation of water.Measurement data of the considered A/C-plant shows that the required performance in the aircondition technology could be achieved. The system represents thus an alternative to airconditioning by application of a conventional refrigeration system. Its advantage is a clearreduction of the required electrical power input in the summer and a reduced energyrequirement in relation to systems which works by cooling the air below the dew point.