In Cuba circulate two types of currencies: the Cuban Peso (CUP), which is the official currency; And the Convertible Peso (CUC) that is used in commercial entities linked to tourism.
We advise that before making the change of currency try to establish differences between the CUC and the CUP. The first has value to buy in most of the tourist establishments of the country and its equivalent is: 1 CUC x 24 CUP, with the latter can buy in some markets, cafes and pay for public transportation. The rate for this exchange rate is fixed.
For the sake of foreign visitors, it is recommended that you exchange your money only in Banks or Exchange Houses (CADECAS) that exist in the airport, hotels and in many places of the country, because, because of their ignorance about these currencies, they could be scammed By unscrupulous people.
Regarding the change of currency, the most favored is the Euro, however you can check the exchange rates of the day: http://www.bc.gob.cu/Espanol/tipo_cambio.asp
Website of the Bank of Cuba http://www.bc.gob.cu