Kizilinler Uyuz Bath, located 15 km to the south of Eskisehir, is a hot spring with a temperature of 38 degrees C and a flow rate of 0.381/sec. Major ion, silica, boron, O-18, H-2 and H-3 analysis was conducted on samples taken from the system to determine the origin, circulation, relationship with shallow subsurface water, the recharge and discharge mechanisms, reservoir temperature and the convergence with cold springs in the vicinity. The cold waters are classified as Ca-HCO3 type water, which is typical of shallow subsurface water, while the hot waters are classified as Na-HCO3 type water, which is typical in deep-circulating underground water, as has been confirmed with isotope analysis. The reservoir rocks of the thermal system consist of ophiolite units with secondary porosity along their fracture and crack systems affected by the tectonic activity in the region. Besides serving as a cap to the typical hot water system recharged by meteoric water, the tuff also creates an impermeable barrier to shallow aquifers in the region.