David Cameron will discuss the Ukraine crisis and EU reform with Herman Van Rompuy at Chequers tonight.
The Prime Minister and the European Council president are due to hold talks over dinner at the country retreat.
Downing Street said the "major areas" they would cover include "priorities" for improving the EU, as Mr Cameron pushes for change after pledging to hold a referendum on British membership if re-elected.
The Prime Minister's spokesman said "not enough progress" had been made implementing last week's Geneva agreement, designed to defuse tensions between Russia and Ukraine.
"We remain of the view that it should be seen through," the spokesman said. "It is important that progress is made in the coming days.
"I don't think enough progress has been made in recent days on this.
"I think you will see the UK, our partners such as the US, the EU as well... will keep making clear the importance of seeing quick progress on this."
Mr Van Rompuy, who has been touring Europe for meetings with leaders, is expected to stay the night at Chequers.