If you’re taking US dollars to Peru, you can exchange them for nuevos soles when you arrive in Lima’s Jorge Chávez International Airport. There are three Interbank casas de cambio (bureau de change/currency exchange) offices in the airport, located in national arrivals, international arrivals and on the second-floor Peru Plaza.If you just want to pay for a taxi to your hotel, you'll find taxi services located within the airport that will accept payment in dollars (check the offered exchange rate before accepting a ride).
If you’ve decided not to take dollars to Peru and you aren’t already carrying nuevos soles, you can withdraw money inside the airport (both nuevos soles and US$). There are Global Net ATMs located throughout Jorge Chávez International (Global Net ATMs are part of Interbank). The surcharge can be high; expect an additional charge of approximately US$3.
According to the Global Net website, Global Net ATMs accept withdrawals using the following international cards: Visa, Visa Electron, Plus, MasterCard, Cirrus, JCB, Discover and American Express. If you have any doubts, ask your local bank for further advice. Always get your bank to clear your card(s) for use abroad before you go to Peru. As a side note, Visa is more widely accepted in Peru than MasterCard.
If you want to avoid all financial considerations at the airport, consider reserving a hotel in Lima that offers a free airport pick-up. Your hotel will collect you upon arrival, leaving you to sort out any money issues once you have settled in.