Proton conducting ionic glasses which consist of only isolated ions were successfully prepared from only CsHSO4 and the mixture of CsHSO4 and CsH2PO4 by melt-quenching technique. The 50CsHSO(4)center dot 50CsH(2)PO(4) glass showed the conductivity of 4.2 x 10(-6)S cm(-1) at room temperature. The 50CsHSO(4)center dot 50CsH(2)PO(4) glass exhibited much higher ionic conductivity than CsHSO4 and Cs-2(HSO4)(H2PO4) crystals in a relatively wide temperature range of ambient to 90 degrees C under dry Ar atmosphere, indicating that vitrification of CsHSO4-based solid acids is effective in enhancing their conductivity. (C) 2009 Elsevier B.V. All rights reserved.