Geochemical studies include new manifestations hunting, sampling, analysis, and interpretation of liquid, gases, and isotopes to understand hydrological pattern that will be displayed through a 2-dimensional geochemical model. Chemical content of geothermal fluid can give us useful information, such as fluid origin, maturity, as well as indication of magmatic activity that can lead to determine the further exploration program in a geothermal area. Geochemical evidences, supported by geological point of view, can be guidance for delineating the focused geophysical investigation area. Chemical geothermometer related to the fluid chemistry and reservoir temperature, become the common method to assess the energy potential from a geothermal prospect area. Beside the exploration stage, geochemical assessment is also very useful in the production stage in order to maintain the sustainability of geothermal energy through identification of injection areas, corrosion studies and possible scaling.