Rio de Janeiro is in Brazil.
Rio de Janeiro . The metropolis is anchor to the Rio de Janeiro metropolitan area , the second-most populous metropolitan area in Brazil and sixth-most populous in the Americas . Rio de Janeiro is the capital of the state of Rio de Janeiro , Brazil 's third-most populous state . The home of many universities and institutes , it is the second-largest center of research and development in Brazil , accounting for 17 % of national scientific output according to 2005 data . Rio de Janeiro ( [ ˈʁi.u dʒi ʒɐˈnejɾu ] ) is one of the 27 states of Brazil .