Hong Kong's new Beijing-backed leader has been sworn in amid rising public discontent over widening inequality and lack of full democracy in the semi-autonomous southern Chinese financial centre.
Tens of thousands of people are expected to take to the streets later in the day in an annual protest that is an occasion for ordinary people to air their grievances over a range of issues.
Leung Chun-ying took office in an early morning ceremony overseen by Chinese president Hu Jintao, becoming Hong Kong's third chief executive since more than a century of British colonial rule ended and China regained control of the city 15 years ago.
There were sporadic clashes between demonstrators and police outside the convention centre where the event took place, and a demonstrator who tried to interrupt Mr Hu as he began his address was bundled away by security officials.
Mr Leung, a 57-year-old police officer's son and self-made millionaire, replaces career bureaucrat Donald Tsang, who took office in 2003 and is barred from another term.
Mr Leung takes over Hong Kong's top job amid swelling public anger over a yawning income gap, sky-rocketing property prices and rising unease about mainland China's growing influence on the semi-autonomous region.
Mr Leung was chosen as chief executive in March, winning 689 votes from a 1,200-seat committee of business elites who mostly voted according to Beijing's wishes.
Hong Kong's 3.4 million registered voters, who can vote for neighbourhood councillors and half of all politicians, had no say.