A novel approach to the synthesis of a low-cost proton-exchange membrane (PEM) based on the single-step preparation of a functionalized ceramic powder containing surface-anchored sulfonic acid (SASA) and a polymer binder, is presented for the first time. The added value of this technique, compared with earlier work published by our group, is the adoption of a direct, single-step synthesis, as opposed to a multiple-step synthesis. The latter requires an oxidation step, in order to convert the thiol group into a sulfonic group. SASA powders of different compositions have been prepared and characterized by means of Brunaur-Emmet-Teller (BET), thermogravimetric analysis-differential thermal analysis (TGA-DTG), differential scanning calorimeter (DSC), Fourier transformation infrared (FT-IR), nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM) and electrochemical techniques. The lowest equivalent weight measured for SASA powders is 1281 g equiv.(-1). The ionic conductivity of a 100-mu m-thick membrane is measured ex situ at room temperature (25 +/- 3 degrees C) and the highest proton conductivity is 48 mS cm(-1). The typical pore size, for the SASA powders is less than 10 nm and ranges from 2 to 50 mn for the SASA-based membranes. The membranes are thermally stable up to 250 degrees C. Direct methanol fuel cells (DMFCs) are assembled with some of the membranes. Preliminary tests showed that the cell resistance for a similar to 100-mu m-thick membrane ranges between 0.29 and 0. 19 ohm cm(2) from 80 to 130 degrees C, respectively, and that the maximum cell power density with a 1 M methanol solution is 127, 208 and 290 mW cm(-2) at 80, 110 and 130 degrees C, respectively, while the corresponding methanol crossover current density is 0.093, 0.238 and 0.281 A cm(-2). (C) 2008 Elsevier B.V. All rights reserved.