Highly conducting, methanol resistant thin films are fabricated using layer-by-layer (LBL) assembly. Pairing a sulfonated aromatic polyether with amine-based polycations yields LBL films with ionic conductivity values up to 3.5 x 10(-2) S cm(-1). Uniformly coating traditional fuel cell membranes with these LBL films (see figure) improves the power output of a direct methanol fuel cell by over 50%.