Recast Nation composite membranes containing three different percentages (5%, 10% and 20%, w/w) of commercial Zirconium(IV) oxide as an inorganic filler were developed by the Doctor-Blade casting technique in order to work in direct hydrogen polymer electrolyte fuel cells (DH-PEFCs) in critical operative conditions for the fuel cell at a temperature of about 120-130 degrees C. By mixing a 10% (w/w) Nafion-dimethylacetammide (DMAc) dispersion with the inorganic compound, composite membranes were prepared. The developed membranes were characterised by water retention capacity (Wup%), ion exchange capacity (IEC, meqg(-1)), thermo-gravimetric analysis and by X-ray measurements. From XRD measurements, the ZrO2 powder insertion was confirmed; the introduced amount was verified by TG analysis that highlighted the major thermal resistance of the developed membranes. Moreover, the chemical-physical results showed an increase of the water uptake and a decrease of the IEC with the increase of inorganic compound percentage. The introduction of the inorganic powder improved the mechanical characteristics of the developed composite membranes. Moreover, the membranes were tested in a 5 cm(2) Commercial single cell from 80 degrees C to 130 degrees C in humidified H-2/air with pressures of 3.0 abs. bar and the obtained results compared to a bare Nafion recast membrane (N16) developed through the same method and used as a reference. Power density values of 604 mW cm(-2) and of 387 mW cm(-2) were obtained at 0.6 V and at T= 110 degrees C (100% of relative humidity) and T= 130 degrees C (85% RH), respectively, for the composite ZrO2-Naflon membrane containing 10% (w/w) of inorganic filler. (c) 2006 Elsevier B.V. All rights reserved.