Money for tourists is CUC or Convertible pesos.
Two types of coins circulate in Cuba: the Cuban Peso (CUP or MN) and the Cuban Convertible Peso (CUC), both contain 100 cents. The CUC is broadcast for the first time in Cuba in 1994 and at the time of writing this page, a CUC equals twenty-four Cuban pesos. The bills in circulation are 1, 3, 5, 10, 20, 50 and 100 CUC and the coins are 1, 5, 10, 25, 50 and 100 cents (1 CUC).
Both the Cuban Peso and the Cuban Convertible Peso can only be obtained and used in Cuban territory. You can get CUC when you arrive in Cuba by exchanging Euros, US or Canadian dollars, sterling or other currencies. The currency exchange service is provided at airports, hotels, banks and Exchange Houses (CADECA), which are present throughout the island, working some of these entities 24 hours a day, 7 days a week.
The CUC exchange rate you will find upon arrival in Cuba is published daily on the Banco Metropolitano website.
You will find that the CUC exchange rate at airports is slightly less favorable, so it is best that upon arrival only change what you might need in the first days. Later you can change the rest of your money in any bank, hotel or CADECA.
Credit cards accepted in Cuba (unless are Amex or from an American Institute), both to pay for goods and services purchased, and to withdraw money at ATMs, are International Master Card and International Visa.
In Havana City you can find ATMs in many places. There are ATMs in almost all banks and major hotels, as well as in some Exchange Houses (CADECA). You can also find ATMs in the main cities of Cuba such as Matanzas, Cienfuegos, Santiago de Cuba, or in tourist resorts such as Varadero and in the keys. However, if you are visiting a small city or town, be sure to bring the necessary cash with you.