TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The sulfonated phosphazene polymer comprises (alkyl)phenoxy side chains (preferably 3-methylphenoxy). The alkylphenoxy side chains contain sulfonic acid fixed-charge groups to impart an ion-exchange capacity (IEC) of 0.8-1.9 mmol/g of dry polymer. The phosphazene polymer may also comprise a blend of sulfonated poly(bis(3-methylphenoxy)phosphazene) and a high glass-transition temperature polymer that can be polyimide or polyetherimide (preferably poly(bisphenol A-co-4-nitrophthalic anhydride-co-1,3-phenylenediamine)).Preferred Method: The chemical cross-links are formed between the main chains of the sulfonated phosphazene polymer, or in the dry polymer film by an ultraviolet (UV) light and a photoinitiator or by a gamma-radiation. The physical cross-links are created by blending the sulfonated phosphazene polymer with a non-sulfonated polymer(s). The membrane can be formed from a casting solution consisting of sulfonated phosphazene polymer and the monomer constituent of the high glass-transition temperature polymer. The membrane can be impregnated into a micro-porous membrane. Preferred Membrane: The membrane is poly(bis(3-methylphenoxy)phosphazene) having an ion-exchange capacity of 1.4 mmol/g dry polymer and is ultraviolet cross-linked using 15% benzophenone.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The photo-initiator is benzophenone having a concentration of 5-25 wt.%. EXAMPLE - Two poly(bis(3-methylphenoxy)phosphazene), each having an IEC of 1.4-1.6 mmol/g and 0-1 mmol/g were dissolved separately in N,N-dimethylacetamide (2-10 wt.%). The solution was stirred at 40-50degreesC for 24 hours. Specified amount of high and low IEC polymer/dimethylacetamide solutions were combined and stirred at 40-50degreesC for 10 hours.    The resulting solution was spread on a clean and flat surface and the solvent was evaporated at 60-70degreesC for 2-3 days to obtained proton-exchange membrane. After complete solvent removal, the membrane was exposed to ultraviolet (UV) light to react all of the photoinitiator.