Non-woven nanofiber mats of poly(styrene sulfonic acid-co-maleic anhydride) (PSSAMA) and poly(vinyl alcohol) (PVA) were prepared by electrospinning using water as solvent. Composite membranes were prepared by casting a poly(methyl methacrylate) (PMMA) chloroform solution over the PSSAMA/PVA nanofibrous mats. Scanning electron microscopy (SEM) showed that these composite membranes are dense structures formed by fibers with average diameter of about 300 nm which acts as composite filler and proton conducting channels. The proton conducting behavior of these membranes were evaluated by impedance spectroscopy in dry atmosphere and in deionized water. The best proton conductivity of this new type of composite electrolyte membrane was 1.67 mS/cm in a dry state, value which is lower than that of commercial Nafion membrane, in the same condition (9.24 mS/cm). Proton conductivity increased with temperature increase, up to 50 A degrees C, when it reached the maximum value.