The present study focuses on preparation of ENR-50/PEMA-NH4CF3SO3 proton conducting polymer electrolytes by solution casting technique. Conductivity increases with NH4CF3SO3 concentration up to 40 wt.% but decreases with further increase in salt content. The temperature dependent conductivity study shows that the conductivity-temperature behaviour of ENR-50/PEMA-NH4CF3SO3 electrolytes follows the VTF rule. DSC studies show that the Tg increases with increase in salt content. This means that the increase in conductivity of ENR-50/PEMA-NH4CF3SO3 is incorrelated to the increase of the segmental motion of the host polymer chains but may be attributed to the increase in the concentration and migration rate of charge carriers.