President: Petro Poroshenko
Petro Poroshenko won the presidential election of May 2014 at a time of crisis which saw the ouster of his predecessor, the loss of the region of Crimea to Russia and a Russian-backed separatist rebellion in the east of the country.
Mr Poroshenko, a billionaire chocolate factory owner, won an unprecedented first round victory in the elections which were held three months after pro-Russian President Viktor Yanukovych was chased from office by crowds following months of street protests.
Mr Poroshenko signed a landmark trade deal with the European Union which had been at the heart of the crisis. Mr Yanukovych's last-minute rejection of the deal and decision to seek a Russian bailout triggered protests which led to his ouster.
Mr Poroshenko promised dialogue with residents of eastern Ukraine and to guarantee their rights, including the right to use Russian in official dealings.
But a ceasefire with the Russian-backed separatists in the eastern provinces of Donetsk and Luhansk in September broke down within weeks, and unrecognised local polls in November elected leaders for two "people's republics" in those provinces.
This move confirmed fears that the tensions between Ukraine and Russia could harden into another post-Soviet "frozen conflict", with separatist regions permanently under the protection of Russian troops as in Moldova and Georgia.