A micro-arc oxidation alumina (MOA) support filled with a CsH2PO4 proton conductor was investigated as an inorganic composite electrolyte for a H-2/O-2 solid-acid fuel cell (SAFC). The MOA support was polycrystalline and contained alpha- and gamma-Al2O3 phases; while, the proton conductor CsH2PO4 formed an interlaced network within the MOA support. The single-module SAFC using the fabricated MOA/CsH2PO4 membrane delivered a peak power of similar to 38.5 m W cm(-2) and a proton conductivity of similar to 2.1 m S cm(-1) at a low temperature (25 degrees C). Compared to a SAFC using an anodic alumina membrane composite electrolyte (AAM/CsH2PO4 SAFC), which displayed rapid degradation, the SAFC using the MOA/CsH2PO4 composite electrolyte showed improved stability with cycling. This was attributed to the crystalline alpha-Al2O3 phase that was part of the MOA support that had increased the chemical resistance. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.