The ECB is meeting Thursday, and traders are expecting details of the bank's plan. Expectations have been high since July, when ECB President Mario Draghi said the bank will do whatever it takes to save the single currency. However, he hasn't yet offered concrete details.
The ECB could announce a new bond-buying program to help cut borrowing costs for Spain and Italy.
The euro rose to $1.2599 in late trading Wednesday from $1.2571 late Tuesday. The British pound rose to $1.5904 from $1.5879.
The dollar fell to 78.41 Japanese yen from 78.45 yen. It rose to 99.06 Canadian cents from 98.56 Canadian cents.
The dollar was practically unchanged at 0.9556 Swiss franc from 0.9555 Swiss franc Tuesday.