In this paper, a new kind of copolymer methyl methacrylate and 2-acrylamido-2-methyl-l-propanesulfonic acid (PAMPS-co-MMA) was synthesized by free radical polymerization. IR-spectrum and 1 H NMR were used to confirm the structure of the copolymers, and the thermal character of the copolymers was investigated with TGA and DSC. Flexible and transparent membranes based on this kind of copolymer were prepared by solution casting method. The physical properties including ionic exchange capability (IEC), water uptake, proton conductivity, methanol permeability and morphology of the membranes were investigated. These membranes showed higher water uptake though they had lower IEC compared with Nation-117. The proton conductivity of the membrane with IEC of 0.9 mmol/g was 1.14 x 10(-2) S/cm and its methanol permeability coefficient was 5.46 x 10(-17) CM2/S, much lower than that of Nafion-117. Tests on cells were also carried out to measure the performance of the membrane. (c) 2007 Elsevier Ltd. All rights reserved.