This paper reports the first study that investigates H3PO4-imbibed polyacrylamide/poly(vinyl alcohol) (PAM/PVA) semi-interpenetrating polymer network (semi-IPN) hydrogel as a high-temperature proton exchange membrane (PEM). The extraordinary ability of the PAM/PVA hydrogel to absorb a large quantity of aqueous solution is fully utilized to achieve a high H3PO4 loading, resulting in high proton conductivity membranes. The anhydrous proton conductivity of a PAM/PVA semi-IPN hydrogel loaded with 73.5 wt% H3PO4 reaches 0.0525 S cm(-1) at 183 degrees C in dry air. A fuel cell using the thick-film PAM/PVA hydrogel exhibits a peak power density of 0.225 W cm(-2) at 183 degrees C with pure O-2 and H-2 as the oxidant and fuel, respectively. The synthesized membrane also shows excellent acid retention under mechanical load and high humidity, a valued characteristic for high-temperature PEMs. These performance-ensuring properties paired with a low-cost synthesis approach demonstrate the new membrane to be a viable candidate as a high-temperature PEM. (C) 2012 Elsevier B.V. All rights reserved.