NOVELTY - Electrolyte material preparation involves mixing polyvinylidene fluoride powder in an organic solvent (10-15 ml) at 80-100 degrees C with continuous stirring for 0.5 hours to obtain mixture. The obtained mixture is cooled to obtain colorless transparent solution, which is mixed with quaternary ammonium hydroxide solution (2.77mol/l) in volume ratio of 50:0.3, and then added in volume ratio of 50:1.2 to obtain the solution. The obtained solution is heated under nitrogen gas at 30-40 degrees C with continuous stirring for 1-2 hours to obtain the solution, which is kept at upper portion of glass plate.    USE - Method for preparing electrolyte material (claimed) used in fuel battery.    ADVANTAGE - The method enables to prepare electrolyte material in simple and cost-effective manner.    DETAILED DESCRIPTION - Electrolyte material preparation involves mixing polyvinylidene fluoride powder in an organic solvent (10-15 ml) at 80-100 degrees C with continuous stirring for 0.5 hours to obtain mixture. The obtained mixture is cooled to obtain colorless transparent solution, which is mixed with quaternary ammonium hydroxide solution (2.77mol/l) in volume ratio of 50:0.3, and then added in volume ratio of 50:1.2 to obtain the solution. The obtained solution is heated under nitrogen gas at 30-40 degrees C with continuous stirring for 1-2 hours to obtain the solution. The obtained solution is kept at upper portion of glass plate, and then dried in vacuum drying box to obtain modified polyvinylidene fluoride film. The obtained polyvinylidene fluoride film (5-8 pts.wt.) is mixed with styrene (75-72 pts.wt.), tetrahydrofuran (18 pts.wt.) and initiator (2 pts.wt.) in a bottle with continuous stirring for 5-10 minutes to obtain solution. The obtained solution is heated at 80-100 degrees C for 8 hours in an oil bath under nitrogen atmosphere to obtain product. The obtained product is extracted with methylene dichloride for 2 hours to obtain product, which is washed with dichloromethane and deionized water to obtain graft film. The obtained graft film is mixed with concentrated sulfuric acid at 80 degrees C for 2 hours to obtain product, which is washed with deionized water to obtain desired product.