Patent ID: 6864006

Claim:
A proton-conducting membrane, comprising a three-dimensionally crosslinked silicon-oxyaen structure (A), carbon-containing compound (B), and inorganic acid (C), characterized by a phase-separated structure containing a carbon-containing phase containing at least 80% by volume of the carbon-containing compound (B), and inorganic phase containing at least 80% by volume of the inorganic acid (C), the inorganic phase forming the continuous ion-conducting paths, wherein said carbon-containing compound (B) is characterized by the skeleton section substituted with hydrogen at the joint with the three-dimensionally crosslinked silicon-oxygen structure (A), satisfying the following relationship: (δ p 2 +δh 2 ) 1/2 <7(Mpa) 1/2 wherein, δp and δh are the polarity and hydrogen bond components of the three-component solubility parameter.