Gano thermal spring is a karst spring located in the Zagros zone in southern Iran. Samples were collected in different seasons from this spring water. In addition to physicochemical factors, major and minor ions and dissolved radon concentration were measured at the sampling site using a RAD7 detector. The annual average temperature and electrical conductivity (EC) of Gano water spring is 41.2ºC and 17,417.5 μs/cm. The pH is in the neutral range and average TDS is 10,442.5 mg/l. The water type is Na-Cl. High Concentrations of Na, Cl, and SO₄ ions probably result from the Hormoz Series salt domes and the dissolution of halite, gypsum, and anhydrite. The Ca/Mg ratio in spring water indicates that the reservoir rocks are dolomitic limestone. Concentrations of elements such as Ag, Hg, Cd, Sn, Pb, Cr, Co, and Bi in Gano water varies from less than 0.5 to 1 μg/l. The mean concentration of ²²²Rn in Gano water is 29.2 kBq/m³, so Gano is not a radon mineral spring. Mean annual effective ²²²Rn doses for inhalation from the waters of Gano spring was computed to be 0.002 μSvy^-1, which is less than the reference level recommended by WHO.