The rapid growth of geothermal power plants is due to their great potential and environmentally friendly energy source. In its development, hydrogen is used as energy storage for several intermittent renewable energy sources. Hydrogen Steam Superheating utilizing hydrogen products can pressure steam as additional fuel to operate steam turbines. The electrolysis method with high-temperature water fluid produces more hydrogen content and is more efficient than ambient temperature water; therefore, it is suitable for producing superheating hydrogen steam by electrolysis using geothermal power plants. A combined cycle (flash & binary) geothermal power plant with additional hydrogen steam superheating can increase the power 8 - 9 MW using the mixed working fluid R-31-10 and RC-318 in a binary cycle power plant and improve the thermal efficiency of flash cycles by up to 12.3%. Thus, the application of adding hydrogen steam superheating is a method that can be utilized to increase the power capacity of geothermal power plants, replacing the current conventional method of drilling to open steam production wells.