Nitrogen is the important element for plants to live, and it just can be absorbed by plants in the simpler compounds form, which is nitrate. Contact Glow Discharge Electrolysis (CGDE) is a technology for the synthesis of new materials with the reactive species such as hydroxyl radicals and electrons are produced, including fixation of nitrogen from the air into nitrate solutions, which is the liquid fertilizer for plants. This research aims to determine how the nitrate solution can be formed through CGDE process and the influence of potassium sulfate concentration as its electrolyte solution. The process is carried out at optimum power obtained from the results of plasma electrolysis current-voltage characterization. The concentration of nitrate formed was tested quantitatively using the UV-Vis spectrophotometry method. The results of this research show that the greater the concentration of electrolytes increase the nitrate productivity, but the specific energy consumption needed is decrease. Nitrate formed is able to reach 279.44 ppm at the highest K2SO4 concentration, which is 0.04 M. These results indicate that nitrates can be produced effectively by the CGDE method.