Formosa Province is a province in northeastern Argentina, part of the Gran Chaco Region. Formosa's northeast end touches Asunción, Paraguay, and the province borders the provinces of Chaco and Salta to its south and west, respectively. The capital is Formosa.

The Gran Chaco or Dry Chaco is a sparsely populated, hot and semiarid lowland tropical dry broadleaf forest natural region of the Río de la Plata basin, divided among eastern Bolivia, western Paraguay, northern Argentina, and a portion of the Brazilian states of Mato Grosso and Mato Grosso do Sul, where it is connected with the Pantanal region. This land is sometimes called the Chaco Plain.