The isotope and geochemical data on the radon-rich waters of the Novobibeyevo occurrence and geochemistry of the water-bearing rocks have been obtained. The waters are predominantly fresh (TDS from 385 to 818 mg/L), with HCO3 Mg-Ca composition and neutral pH. The geochemical parameters vary from reductive to oxidative. Si content is 5.77-13.30 mg/L. The determined range of 222Rn activity is 4 to 429 Bq/ L; isotope concentrations are 5.25·10-4 to 0.125 mg/L 238U, 1.86·10-7 to 2.43·10-5232Th and 9.28·10-10 to 2.08·10-9226Ra. The 232Th/238U ratio in the waters is in the range 2.63·10-5 to 2.92·10-2. Total β-activity varies from 11 to 65 mBq/ L. The activity (mBq/ L) is up to 281 for 234U, 153 for 238U, 76 for 226Ra and 25.4 for 228Ra. The uranium isotope ratio (γ) 234U/238U in radon waters varies from 1.30-1.84. The isotope composition of the waters testifies to their meteoric infiltration origin. The δ18O values range from -18.9 to -14.4, and δD ranges from -139.4 to -112.5‰ The obtained δ13CDIC values are within -14.2-10.0‰ , with DIC content 3.4 to 8.7 mmol/L. The main source of water-dissolved carbon dioxide is soil carbon dioxide of mixed origin. The waters are hosted by biotite granites, moderately alkaline mylotinized biotite granites, and biotite porphyry granites. Dykes of olivine diorites and porphyry dolerites have been revealed. By petrochemical composition, the rocks lie in the zone of subalkalic granites. Minerals-concentrators of radioactive elements have been identified, with thorium and uranium concentrations of 0.53 at. % and 0.44 at. %, respectively. Naturally, radon waters show the highest concentrations (mg/L) of Si (up to 8.85), Mn (up to 0.22), Fe (up to 0.34), Sr (up to 0.77), and Ba (up to 0.13). Br, I, Se, Te, Re and U are concentrated in the waters on the account of high migration ability.
