Removal of multicomponent moisture is a frequent problem in pharmaceutical and related industries. To control the process temperature of the solid and individual drying rates must be known. For nonporous (crystalline) solids of small size the problem may be reduced to simulation of a wet-bulb wetted with multi-component moisture. In the paper a simple model of the process was presented and tested using the wet-bulb of a commercial Assmann psychrometer as a test solid. Dynamics of temperature change of such wet-bulb wetted with a binary mixture of ethanol and water was measured and compared with those predicted by the model. Satisfactory agreement of the model predictions with the experiment was found.