A new class of crosslinked proton-conducting membranes (CPMs) with polyoxyalkylene moieties was designed and prepared based on poly(styrene-co-maleic anhydride) modified with 2-aminoethanesulfonic acid sodium salt (AESA-Na) and polyoxyalkylenediamines (PEGDAs). The number density of the pendant of sulfonate group was controlled by the ratio of AESA-Na to PEGDA. The resulted membranes possess good mechanical strength and excellent flexibility. The structural characterizations of these membranes were confirmed by FT-IR and solid-state C-13 NMR spectra. All these membranes exhibit a wholly amorphous morphology, and show a one-step weight loss from 350 degrees C, indicating their good thermal stability. The CPM sample with 1.25 mequiv SO3H per gram reaches the proton conductivity of 0.21 S cm(-1) at 30 degrees C and 0.49 S cm(-1) at 95 degrees C, respectively. Moreover, these protonated membranes show adequate oxidative stability in Fenton's reagent at 30 degrees C. (c) 2008 Elsevier Ltd. All rights reserved.