El Salvador´s currency is the dollar as of 2004. There are ATM´S in every mall, gas station and banks that are open 24/7.

All major credit cards are accepted, and withdrawals against credit cards may be done at banks. Banks in El Salvador are owned by international banks such as citigroup, GE,  Scotiabank, HSBC and others.

If you plan to travel outside of San Salvador, don't count on traveler's checks being a recognized entity. In many of the rural areas (unlike, say, rural Mexico) even banks with international branches may not understand the concept and/or may require as many as 12 steps PER CHECK in order to cash one of your traveler's checks. They also sometimes try to require the receipts, finding it suspicious that you left them back home as advised.