In Poland the official currency is zloty (PLN), often abbrieviated to zl. You can exchange all major currencies into zloty at many places in Poznan. The current exchange rate is app. 3 zl for 1 USD and 4 zl for 1 Euro. The rate can vary from day to day. Also, it is now easy to get cash advance on major credit cards, at several ATM's and banks located downtown and near the conference center.