A composite membrane composed of iron oxide and polyvinyl alcohol (PVA) was investigated as an alternative electrolyte material for proton exchange membranes (PEMs) in fuel cells using hydrogen as a fuel. Acetic acid (AA)-stabilized lepidocrocite (γ-FeOOH) nanoparticles and goethite (α-FeOOH) nanoparticles (ferroxane) were mixed with dissolved PVA and air-dried to fabricate the PEMs. The ferroxane–PVA composite membrane showed higher proton conductivity than goethite–PVA composite membrane. However, the proton conductivities of the ferroxane–PVA composite membrane decreased as PVA content in the composite membranes increased. Fourier transform infrared spectroscopy analyses of the ferroxane–PVA composite membrane showed that a large portion of AA groups on the surface of ferroxane nanoparticles was lost when mixed with PVA. The tensile force resistance of the composite membrane was much higher compared with ferroxane-derived ceramic membranes.