The euro held near a four-month high against the greenback after Germany's constitutional court gave the green light for Berlin to ratify the euro zone's permanent rescue fund.
The Swiss National Bank, which holds a monetary policy announcement at 0730 GMT, capped the franc at 1.20 per euro a year ago to shield the economy from deflation and a recession. For the past year the franc has largely been trading in tandem with the euro against the dollar.
Analysts in a Reuters poll expect the SNB to keep interest rates extremely low and to reaffirm its commitment to capping the franc.
"The SNB is (expected) to leave the lower boundary in EURCHF unchanged at 1.20 for at least one more quarter," UBS economist Reto Huenerwadel said. "Probably more interesting than the SNB's actual monetary decisions, however, will be any changes to their underlying Swiss and global outlook."
The economy, which long seemed immune to the problems besetting the neighbouring euro zone, unexpectedly contracted in the second quarter. According to the Reuters poll of analysts, the SNB is expected to cut its growth forecast for this year to 1 percent from around 1.5 percent.
Producer and import price data for August is due at 0715 GMT, and could also indicate a softening of the economy.
The franc rose 0.1 percent against the dollar to trade at 0.9362 at 0539 GMT compared to the New York close. It hit a high of 0.93589 on trading platform EBS on Wednesday, its lowest since mid-May.
The franc fell 0.1 percent against the euro to 1.2096.