the official language in rio de janeiro is portuguese -  brazil happens to be the only portuguese speaking country in the western hemisphere, and in all of latin america - this can be quite baffling for many since spanish is the spoken language everyone associates with south american.

while cariocas might speak english or spanish, it is always a good idea to acquire basic portuguese knowledge - communicating can prove to be difficult without this entry level vocabulary - the residents of rio de janeiro are extremely cordial and good-humoured people, so interacting with those who cannot speak the same language can prove to be an interesting interaction.