The synergetic proton conducting effect was observed in an acid-base composite composed of phosphonic acid functionalized polysulfone (PSF-PA) and triazolyl functionalized polysulfone (PSF-CH2-iPrOHTri), with three orders of magnitude improvement compared to that of the acidic or basic component. The maximum proton conductivity of 42.71 mS cm(-1) at 100 degrees C and 90% RH was observed in PSF-PA/PSF-CH2-iPrOHTri composite membrane composed of 75.0% PSF-CH2-iPrOHTri. In addition, the acid-base composite membrane showed higher thermal and oxidative stability, reduced hydrophilicity and methanol permeability, significantly improved mechanical strength. For the hydrated membranes of PSF-PA or PSF-CH2-iPrOHTri, the tensile strengths showed significant degradation with values only about halves of the dry membranes. On the other side, the tensile strength of the acid-base composite composed of 75.0% PSF-CH2-iPrOHTri showed only slight drop from 35.52 MPa to 30.59 MPa. (C) 2016 Elsevier B.V. All rights reserved.