TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Group: The polyelectrolyte material contains ionic group chosen from sulfonic acid having density of 0.1-5 mmol/g, preferably 0.5-3.5 mmol/g and more preferably 1-3.5 mmol/g, sulfonimide, sulfate, phosphonic acid, phosphoric acid and carboxylic acid.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Group: The polyelectrolyte material contains ionic group chosen from sulfonic acid having density of 0.1-5 mmol/g, preferably 0.5-3.5 mmol/g and more preferably 1-3.5 mmol/g, sulfonimide, sulfate, phosphonic acid, phosphoric acid and carboxylic acid.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The fuel supplied to the membrane-electrode composite material contains mixture of 1-6C organic compound (20-70 wt.%) and water.    TECHNOLOGY FOCUS - POLYMERS - Preferred Properties: The fraction (Rw2) of non-frozen water is 50-100 wt.%, calculated using the formula: Rw2=(Wnf/(Wnf+Wfc+Wf))x100, where Wf is bulk water quantity per dry weight of 1 g of polyelectrolyte material. Wnf is 0.05-2. The polyelectrolyte material has non-bridge structure, and is film-like and has Rw1 of 60 wt.% or more. The methanol permeation amount of the material per unit area with respect to 30 wt.% methanol aqueous solution is less than 40 micronsol.minute-1.cm-2, and the methanol permeation amount per unit area and unit thickness with respect to 30 wt.% methanol aqueous solution is less than 1000 nmol.minute-1.cm-1. The material has proton conductivity of more than 4S.cm-2/unit area per unit thickness, total light transmittance in water containing state of 30% or more, average of pore size of 5-80 vol.% and space of less than 50 nm.Preferred Material: The photoelectrolyte material contains aromatic phosphorus group polymer of formula: -P(=X)(-R1)-.R1=organic group;andX=oxygen, sulfur or selenium.The phosphorus type polymer has carbon-phosphorus-carbon bond in principal chain. The polymer is preferably aromatic polyether phosphine oxide, aromatic poly(ether phosphine oxide/ether ketone) copolymer. The material has cross-linked structure dependent on radiation induced cross-linking and further contains bivalent group having aromatic ring of formula (II, III, IV-2 or IV-3). The polymer is of formula (V).R2-R4=H, halogen, univalent organic group or ionic group;a-e=0-4;Z=direct bond, -O-, -S-, -Se-, -CQ1Q2-, alkylene, arylene, alkylidene or cycloalkylidene, preferably direct bond or -CQ1Q2-;Q1,Q2=H, halogen, (halo)alkyl or aryl;Ar1-Ar4=aryl or arylene group;dotted line=optional bond;R5-R8=R2 excluding H;f,g=0-5;d+e+f+g=2 or more;E=bivalent group having aromatic ring of formula (II, III, IV-2 or IV-3);Ar5,Ar6=bivalent arylene;W=bivalent electron withdrawal group chosen from -CO-, -SO2- or -P(R1)O-, preferably -CO- ;R1=organic group;Y=-O-, -S- or -Se-.