The 53-year-old Tymoshenko, who suffered severe back problems during her 2½ years in prison, spoke to the crowd from a wheelchair and appeared close to exhaustion.
But her flair for vivid words was undimmed.
"You are heroes, you are the best thing in Ukraine!" she said of those killed in the violence. The Health Ministry today said the death toll in clashes between protesters and police that included sniper attacks had reached 82.
After the protests forced the rerun of a presidential election nominally won by her foe Viktor Yanukovych, Tymoshenko became prime minister. But when Yanukovych won the 2010 election, Tymoshenko was arrested and put on trial for abuse of office, an action widely seen as political revenge.
Now Yanukovych once again appears on the wane and Tymoshenko on the rise. After yesterday's agreement between the president and the opposition that reduced Yanukovych's powers, Yanukovych has gone to Kharkiv in his support base of eastern Ukraine, leaving the capital effectively in the control of the opposition.