Termas de Río Hondo is a spa city in Santiago del Estero Province, Argentina. It is located on the banks of the Dulce River, about 65 kilometres north of the provincial capital, Santiago del Estero, near the artificial Río Hondo Lake.
According to the 2001 census conducted by INDEC, the city had a population of 27,838 inhabitants. Its setting on the Dulce River and beside the Río Hondo reservoir places it within the river and lake system of northern Argentina.
The city is known as a spa destination, a characteristic reflected in its name, and its position near the Río Hondo Lake is among its defining geographic features.