Pay with the Euro
You pay in Rotterdam with the Euro like within most other European countries. Notes are in denominations of €500, 200, 100, 50, 20, 10 and 5. Coins are in denominations of €2 and 1, and 50, 20, 10, 5, 2 and 1 cents. Please note that most shops round the amount you have to pay till 5 cents, which means the 1 and 2 cent coins are hardly used. So don't get surprised when you don't get 1 or 2 cent change when you pay.
Using your bankcard in Rotterdam
You can find cash machines at almost every corner of the street as well as at most stations. You can get your bankcard to get cash from these machines. During the weekend there can be long queues for the cash machines in the shopping areas, so it makes sense to get some cash at home before travelling to Rotterdam. You can use your bankcard to pay in shops as well; it's the most used payment method.
Paying with creditcards
In the bigger shops and in almost all restaurants the major creditcards are accepted as well. Most small shops and supermarkets don't accept creditcards however. Visa and Mastercard are more generally accepted than American Express.
You can exchange money at the bank offices or at the GWK exchange offices, which you can find at Rotterdam Central station. Hotels tend to charge high commissions but do exchange money as well.