The mechanical stability of thin-film polymer-ceramic composite membranes has been evaluated in a variety of processing steps with temperatures ranging from 25 to 350 degrees C. Although not measured in this work, references for similar materials indicate that the coefficients of thermal expansion for the two layers of the membrane are considerably different. Upon heating, this difference led to the development of thermally-induced stresses. These stress could be relieved if the membrane were heated in an unrestrained manner; however, they were sufficient to cause membrane failure if not relaxed. Heating to temperatures above the glass transition of the polymer resulted in defect formation in that layer due to flow into the ceramic support. These results indicate that, if properly handled, the membranes are sufficiently stable to be used over a wide range of temperatures. However, serious consideration must be given to these issues in the design of larger-scale devices.