Ukrainian Prime Minister Yulia Tymoshenko chose Brussels, not Moscow, for her first foreign visit since her cabinet was approved in December after months of political turbulence, underlining her pro-Western credentials.
"After ... the creation of a new government, we have now have a sense of unity as far as our wish for European integration is concerned," Tymoshenko said.
"The time has come for our relations to take on an entirely new dimension," she told a joint news conference after meeting European Commission President Jose Manuel Barroso.
Politics in Ukraine have remained turbulent since the 2004 "Orange Revolution" brought President Viktor Yushchenko to power.
"To achieve progress we need political stability, we need a Ukraine that is really committed to political and economic reforms," Barroso said after the meeting.
Tymoshenko has settled her differences with Yushchenko, who also strongly backs Ukraine's drive to join the EU one day.
But the wafer-thin majority she received in parliament for her cabinet augurs ill for reform, analysts say.
The EU has so far not offered Ukraine the prospect of full membership, opting for close political cooperation and a future free trade zone with the country that is a major transit route for energy to the West.
Barroso pledged the EU would soon start talks with Ukraine on a free trade pact after Brussels this month cleared the way for the country to join the World Trade Organisation.
During her two-day trip, Tymoshenko was to meet NATO officials. She favours NATO membership for her country, but Ukrainians are deeply divided on joining the military pact, a move strongly opposed by neighbour Russia.
Tymoshenko reiterated promises to make Ukrainian politics honest and transparent after international watchdogs repeatedly said the country has been plagued by corruption.
Transparency would apply to energy policy, she added.