Linear meta-polyaniline (m-PAni) has been synthesized and proton-conducting polymer membranes have been prepared through solution casting of acid-doped m-PAni. The obtained membranes show good proton conductivities at temperatures above 100 degrees C, achieving 10(-2.7) S/cm at 120 degrees C under extremely low-humidity conditions. The effect of doping acids, doping levels and humidity, on the conductivity is discussed. (C) 2008 Elsevier B.V All rights reserved.