Ever since the Argentine peso was devalued in 2002, U.S. dollars haven't been widely accepted, so you need pesos. In the Ezeiza airport you can exchange money at Casa Piano and Banco Nación in Terminal A on the ground level. You can also hit the ATM in Terminal A, extracting pesos at a decent exchange rate. If you're taking licensed transportation into town, you can pay in dollars or euros at the stands next to the arrival gates.
Of course, while conducting any financial transaction, be aware of your surroundings and don't flash cash on the street. Staffers at exchange houses will require a passport or ID card to conduct transactions. An easier option is to ask your hotel to change your money; most now offer better rates, rivaling those at exchange houses.
You can find ATMs throughout the city. Those that are part of the Banelco network are the most prevalent. They're identified by a burgundy sign, and you'll find them in banks, service stations, and malls.
American Express (Arenales 707, El Centro. 11/4310-3000). Banco Piano (San Martín 345, El Centro. 11/4394-2463). BankBoston (Florida 99, El Centro. 11/4820-2000). Cambio America (Sarmiento 501, El Centro. 11/4393-0054). Citibank (Florida 199, El Centro. 11/4329-1000). Forex Cambio (M. T. de Alvear 540, El Centro. 11/4010-2000). HSBC Republic (Florida 201, El Centro. 11/4320-2800). Western Union (J. L. Borges 2472, Palermo. 11/4777-1940).
