Tocantins (Brazilian Portuguese: [tokɐ̃ˈtʃĩs] (listen)) is one of the 26 states of Brazil. It is the newest state, formed in 1988 and encompassing what had formerly been the northern two-fifths of the state of Goiás. Tocantins covers 277,620.91 square kilometres (107,190.03 sq mi) and had an estimated population of 1,496,880 in 2014. Construction of its capital, Palmas, began in 1989; most of the other cities in the state date to the Portuguese colonial period. With the exception of Araguaína, there are few other cities with a significant population in the state. The government has invested in a new capital, a major hydropower dam, railroads and related infrastructure to develop this primarily agricultural area. The state has 0.75% of the Brazilian population and is responsible for 0.5% of the Brazilian GDP.

Tocantins has attracted hundreds of thousands of new residents, primarily to Palmas. It is building on its hydropower resources. The Araguaia and Tocantins rivers drain the largest watershed that lies entirely inside Brazilian territory. The Rio Tocantins has been dammed for hydropower, creating a large reservoir that has become a center of recreation. Because it is in the central zone of the country, Tocantins has characteristics of the Amazon Basin, and also semi-open pastures, known as cerrado. The Bananal Island (Ilha do Bananal), in the southwest of the State, is the second largest fluvial island in the world. Tocantins is also home to the Araguaia National Park, the Carajás Indian reservations, and Jalapão State Park, which is about 250 kilometres (160 mi) from Palmas. There, the rivers create oases in the dry landscape, attracting many ecotourists to the region.