Poly(acrylic acid) (PAA) is an important polymer frequently used as a superabsorbent in health and hygiene products. As a polyelectrolyte that swells with absorption of water it has potential application in other fields including drug delivery, tissue scaffolds, actuators, and desiccation and humidity control. To be useful in such applications the membrane's mechanical integrity must be maintained while optimizing its moisture absorption properties. In this work PAA membranes are electrospun with lysine as cross-linking agent. The effects of varying the concentration of the lysine on the cross-link density and consequently on the thermo- and hygro-mechanical properties of the membranes are studied through electron microscopy, FTIR spectroscopy, and dynamic mechanical thermal analysis (DMTA). Isothermal glass transitions are shown to occur with varying moisture content. The moisture content (or relative humidity) at which the transition occurs is reduced by increasing temperature and can be controlled by varying the cross-link density. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41252.