John Lee, who has spent most of his civil service career in the police and overseeing security matters, has much less policy-making experience than previous chief executives.
Demands for expanded democracy in the semi-autonomous territory inspired protest movements that were largely ignored by Beijing and crushed by security forces.
The activists were intercepted as they tried to flee to Taiwan by speedboat. Two people accused of organizing the trip got the stiffest penalties, two and three years in prison.
Pro-democracy protests, now in their 10th straight weekend, are posing one of the biggest tests to China's leadership since the 1997 handover from Britain.
Local media are reporting dozens of protesters have been killed. Demonstrators are demanding a quick transition to civilian rule following the ouster of Sudan's president in April.
