Russian President Vladimir Putin and his Ukrainian counterpart Volodymyr Zelensky have arrived in Paris for face-to-face talks for the first time over the conflict that has killed more than 13,000 people.
France and Germany are mediating.
Leaders will try to end five-and-a-half years of fighting in eastern Ukraine between government forces and Russian-backed separatist rebels.
The meeting comes after a major prisoner exchange and the withdrawal of the Ukrainian army from three main frontline areas.
French President Emmanuel Macron and German Chancellor Angela Merkel are hosting talks at the Élysée Palace.
Zelensky's recent military and diplomatic moves are aimed at securing peace, but there has already been angry backlash among his opponents, who have warned against conceding too much to Russia.
Although the chances are slim that the official meeting in Paris will result in a comprehensive peace agreement between Kyiv and Moscow, Russia has spoken of "very cautious optimism" about the leaders' first summit in more than three years.
