One cannot use the Euro in Poland. According to Poland's official travel website, it is not part of the Euro currency zone. The legal tender of the country is the złoty.
Visitors to Poland can exchange currency anywhere in the country, regardless of the size of the city or town where they are. Poland's official travel website states that visitors can exchange all major currencies, including the Euro, at automated telling machines, banks or currency exchange counters. At border crossings, hotels and designated outlets throughout the country, over-the-counter exchange is possible. Many such locations also accept exchanges of major travelers checks. Credit cards are another reliable method of payment for travelers to Poland.