TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The content of metallic phosphorus compound in the electrode catalyst layer is 1-60 wt.%.    TECHNOLOGY FOCUS - POLYMERS - Preferred Polyarylene: The polyarylene consists of structural units of formulae (1,2).Y'=-CO-, -SO2-, -SO-, -CONH-, -COO-, -(CF2)l- or -C(CF3)2-;l=1-10;Z=direct bond, -(CH2)l-, -C(CH3)2-, -O-, or -S-;Ar=aromatic group having substituent of formula: -SO3H, -O(CH2)pSO3H, or -O(CF2)pSO3H;m,n=0-10;k=1-4;A,D=direct bond, -CO-, -SO2-, -SO-, -CONH-, -COO-, -(CF2)l-, -(CH2)l-, -CR'2-, cyclohexylidene, fluorenylidene, -O-, or -S-;R'=aliphatic hydrocarbon, aromatic hydrocarbon, or halogenated hydrocarbon;B'=oxygen or sulfur;R1,R16=H, fluorine, alkyl, partially or fully halogenated alkyl, allyl, aryl, nitro, or nitrile;s,t=0-4;andr=0, or 1 or more. SPECIFIC COMPOUNDS - The metallic phosphorus compound is zirconium phosphate.    EXAMPLE - (In g) 3-(2,5-dichlorobenzoyl) neopentyl benzene sulfonate (90.3), 2,5-dichloro benzophenone (69.1), 4-chlorobenzophenone (1.08), bis (triphenyl phosphine) nickel dichloride (9.81), sodium iodide (2.25), triphenyl phosphine (52.5), zinc (78.4), and dehydrated dimethylacetamide (373 mL) were polymerized for 3 hours at 90degreesC. Dimethylacetamide (1400 mL) was added and the polymerization solution was diluted. The insoluble portion was filtered, the filtrate was poured into methanol, and a polymer was solidified. The precipitated polymer was vacuum-dried, to obtain polyarylene (120) having a number average molecular weight of 39000 and a weight average molecular weight of 153000. Polyarylene (120), dimethylacetamide (970 mL), and lithium bromide (29.3) were stirred at 120degreesC for 7 hours. The reaction solution was poured into acetone (5 L), and a polymer was solidified. The obtained solid was processed with distilled water/concentrated hydrochloric acid solution, washed with distilled water, and dried at 70degreesC for 12 hours to obtain polyarylene (100) having a sulfonic acid group. The polymer had an ion-exchange capacity of 2 meq/g and a weight average molecular weight of 116000. An electrode paste obtained by mixing platinum-supporting carbon particles (1.51), distilled water (0.88), 15 wt.% N-methyl-2-pyrrolidone solution of the sulfonated polyarylene (3.23), N-methyl-2-pyrrolidone (12.47), 10% ethanol liquid (3.05) of zirconium phosphate, and DA234 (RTM: dispersant) (0.028) was applied on a carbon paper to form an electrode catalyst layer. The electrode catalyst layer was used in a fuel cell and evaluated. The initial-stage cell voltage was 0.63 V, 0.62 V after 100 hours, and 0.6 V after 500 hours.