LIQUID COMPOSITION, POLYMER ELECTROLYTE MEMBRANE, MEMBRANE ELECTRODE ASSEMBLY AND POLYMER ELECTROLYTE FUEL CELL

To provide a liquid composition capable of forming a membrane excellent in durability against hydrogen peroxide or peroxide radicals and excellent in hydrogen gas barrier property; a polymer electrolyte membrane; a membrane electrode assembly; and a polymer electrolyte fuel cell. Liquid composition comprising a liquid medium, an acid-type sulfonic acid group-containing fluorocarbon polymer of which the hydrogen gas permeation coefficient under the conditions of a temperature of 80° C. and a relative humidity of 10% is at most 2.5×10cm·cm/(s·cm·cmHg), and cerium atoms; a polymer electrolyte membrane comprising the acid-type sulfonic acid group-containing fluorocarbon polymer, and cerium atoms; and a membrane electrode assembly comprising an anode having a catalyst layer, a cathode having a catalyst layer, and the polymer electrolyte membrane disposed between the anode and the cathode