Composite polymer electrolyte membranes with nano-TiO2 films are fabricated by deposition of titania nanoparticles from a sol solution. Measurements of ion conductivity, methanol permeability and single-cell performance of the modified Nation membranes are conducted. The TiO2 films adhere well and are crack-free. The protonic conductivity of the composite membranes decreases with increasing titania content, but methanol permeability is reduced. Preliminary tests on a single-cell of a direct methanol fuel cell (DMFC) indicate that a titania-coated membrane with 0.009 mg cm(-2) content gives the highest cell voltage and maximum power density. (c) 2005 Elsevier B.V. All rights reserved.