Volume-averaging techniques developed for modeling drying processes in porous materials offer a convenient framework for analyzing vapor sorption in porous hygroscopic polymeric materials. Because of the large temperature changes associated with water vapor sorption in these materials (from 10 degrees to 20 degrees C), sorption/diffusion processes are best characterized through the coupled differential equations describing both the transport of energy and mass through the porous structure. Experimental and numerical results are compared for a variety of natural and man-made porous polymeric materials (textiles) using the volume-averaging technique. Boundary heat and mass transfer coefficients and assumptions about thermal radiative properties of the experimental apparatus are shown to influence results obtained with the numerical solution method.