For applications in gas cooling a thermoacoustic refrigerator may be simplified by using the gas stream itself as the acoustic medium and eliminating the cold heat exchanger by directing the input gas stream through the stack (R. S. Reid et al., ‘‘Cyclic Thermodynamics with Open Flow,’’ Phys. Rev. Lett. to appear May 25, 1998). This concept may be extended to dehumidification, with the incoming humid air stream being cooled to its dew point and condensing water in the thermoacoustic stack. The water will appear as liquid on the stack surface or as a fog and is removed from the resonator, while the dry air flows out of the system. Design problems include collecting and removing the condensate from the stack to the outside of the resonator, and optimizing stack design for a working gas in multiple phases. Experimental results and numerical models for a prototype compressed-air dehumidifier will be presented. [Work supported by DOE Office of Basic Energy Sciences.]