Northeastern Algeria has been known, since ancient times, by the presence of thermo-mineral springs emerging from different geological formations, especially in the vicinity of the Tunisian borderline. These hot waters circulate along the fractured system and the main thermal spring emerges from a Neogene graben. Each of the four inventoried hot springs has at least three griffins. These thermal waters are found to be saline and carbo-gaseous. The geochemical facies are of the Cl–HCO3–Na type. Stable isotopes contents (δ2H, δ18O) showed that the waters are of meteoric origin. Strontium isotopic ratios 87Sr/86Sr indicated the presence of a mixture of thermal fluids with infiltrated meteoric waters at shallow depths as well as strong water-rock interactions. The combined use of geochemical and isotopic tracers highlights the existence of a hydrothermal alteration and a saline fluid circulation.