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A class of inorganic-organic hybrid membranes with low methanol permeability characteristics for possible direct methanol fuel cell (DMFC) applications was architected, formulated, and fabricated through the blending of poly(vinyl alcohol) (PVA) and polyacrylamide (PAM) followed by crosslinking with glutaraldehyde (Glu). Cesium salts of different heteropolyacids, including phosphomolybdic acid (PMA), phosphotungstic acid (PWA), and silicotungstic acid (SWA), were incorporated into the polymer network to form corresponding hybrid membrane materials, namely, PVA-PAMCsPMA-Glu, PVA-PAM-CsPWA-Glu, and PVA-PAMCsSWA-Glu, respectively (where ''Cs'' together with a heteropolyacid abbreviation indicates the cesium salt of that acid). All the three hybrid polymer membranes fabricated exhibited excellent swelling, thermal, oxidative, and additive stability properties with desired proton conductivities in the range 10 À2 S/cm at 50% relative humidity. A dense network formation was achieved through the blending of PVA and PAM and by crosslinking with Glu, which led to an order of magnitude decrease in the methanol permeability compared to the state-of-the-art commercial Nafion 115 membrane. The hybrid membrane containing CsSWA exhibited a very low methanol permeability (1.4 Â 10 À8 cm 2 /s) compared to other membranes containing cesium salt of heteropolyacids such as PMA and PWA. The feasibility of these hybrid membranes as proton-conducting electrolytes in DMFC was investigated, and the preliminary results were compared with those of Nafion 115. The results illustrate the attractive features and suitability of the fabricated hybrid membranes as an electrolyte for DMFC applications.