Lithium ion conductors and proton conductors were developed in support of a large-area electrochromic transparency effort with the goal of identifying a polymer electrolyte that provides high ionic conductivity with good electrochemical and thermal stability. The best lithium ion conductor was found to be a transparent, solid uv-curable poly(alkyleneoxy)acrylate-LiCF3SO3 complex that has excellent thermal stability, and room temperature ionic conductivity on the order of 10(-6) Scm(-1). The addition of 50 wt.% propylene carbonate to the polymer-salt complex increases its conductivity by three orders of magnitude, without degradation of its other physical properties. Two sulfonic acid-based polyelectrolytes were explored as potential proton conductors, a cross-linked poly(2-acrylamido-2-methyl-1-propane sulfonic acid), PAAMPS, which has practical use for temperatures up to about 70 degrees C, and a novel vinyl sulfonic acid/vinylpyrrolidone copolymer that has excellent thermal stability for over 1000h at 90 degrees C. The copolymer has the potential for high conductivity based on its relatively low equivalent weight. Two different electrochromic devices containing the polymer electrolytes are described, and the temperature-dependent switching behavior of the devices is related to the conductivity of the polymer electrolytes.