The stock was up 10.4 percent at 9.05 baht ($0.2513) as of 0324 GMT after rising as far as 9.20 baht, the highest since Nov. 24.
The benchmark index was down 0.46 percent. The flag carrier is Thailand's only airline that flies into the 28-member bloc, with 11 EU destinations.
Europe contributes about 30 percent to 35 percent of Thai Airways' revenue, analysts said.