This study presents new chemical and isotopic data on the two types of cold high pCO² groundwaters located in the Mukhen deposit (Far East of Russia). The first type belongs to HCO₃-Ca-Mg waters with a relatively low TDS (up to 1.7 g/l) and high concentrations of Fe²⁺, Mn²⁺, Ba²⁺, and SiO². The second type is of HCO₃-Na water with high TDS (up to 14 g/l) and elevated Li⁺, B, Sr²⁺, Br^?, and I^?. New isotopic data of water (δ¹⁸O, δD and ³H) and gas (δ¹³CTIC) phases along with a detailed geological and hydrogeological investigation of the study area allowed identifying genesis of both the mineral waters. The residence time of groundwaters were calculated as well. It was established that the origin of the high pCO₂ groundwaters was caused by active faulting and CO₂ venting in the subsurface zone.