Abstract This study aims to establish a reliable method for accurately estimating reservoir temperature in the Patuha Geothermal Field (PGF), a vapor-dominated reservoir. The current power generation is in the southern region of PGF, known for its high potential, while the northern region, a largely underexplored area due to limited subsurface data, presents an intriguing challenge. To address this, multicomponent geothermometry was adopted to assess the northern reservoir temperature. This method utilizes comprehensive chemical analysis and mineral saturation indices (SI) for precise temperature assessments. Optimization identified key minerals for better SI clustering. Multicomponent geothermometry estimated the reservoir temperature at 245°C, while classical solute geothermometry (quartz, chalcedony, Na-K-Ca, Na-K, and K-Mg) provided a range of 220-260 °C. Despite similar results, multicomponent geothermometry is considered more accurate as it accounts for various processes during water ascent. The optimization identified quartz, anhydrite, actinolite, calcite, illite, kaolinite, wairakite, and epidote as minerals, providing better SI clustering. Thus, multicomponent geothermometry outperforms classical solute geothermometry in vapor-dominated reservoirs like PGF, mainly when fluids are not in complete chemical equilibrium with reservoir minerals. This method’s broader application potential for straightforward analysis using standard geochemical data without intricate analyses promises significant advancements in geothermal research.