Temperature tolerant new anhydrous Nafion-1,2,3-triazole blend membranes were prepared by room temperature (RT) and autoclave (AC) solution processing. Both blend membranes were very flexible and stable up to 260 degrees C. Interestingly, they showed very different physico-chemical properties. In this paper, the properties of both the blend membranes were compared by Fourier transform infrared, thermogravimetric-differential thermal analysis, dynamic elastic modulus, X-ray diffraction, small angle X-ray scattering, atomic force microscopy, and proton conductivity. 1,2,3-Triazole was successfully incorporated into the nanostructure of Nafion. The blend membranes were more conductive than Nafion at 200 degrees C under anhydrous conditions, and the conductivity was about 1 mS/cm. The blend membrane using AC solution processing showed higher thermal stability, density, and conductivity than that of RT solution processing. Therefore, an AC solution processing can be expected as a new synthesis method to get electrolyte membranes. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3503598] All rights reserved.