A marching band and flag-waving children dressed in red and white tracksuits greeted the torch at the airport, where it arrived from Vietnam. The flame was then driven to a welcome ceremony at a cultural center.
Five pro-democracy activists tried to disrupt the ceremony, but a dozen police blocked the protesters in a street far from the venue.
"We demand that the Chinese communist regime lives up to the promise it made in 2002 to improve human rights in China," said the protest's leader, maverick lawmaker Leung Kwok-hung. He was heckled by a few onlookers who accused him of stirring up trouble.
About 3,000 police planned to guard the torch Friday during its relay through this former British colony, which returned to Chinese rule 11 years ago.
Meanwhile, Chinese mountaineers made final preparations Wednesday to take the Olympic torch up Mount Everest but a brewing storm made a climb in the next three days unlikely, the Xinhua News Agency reported. It cited Yang Xingguo, the expedition's weather expert at base camp.
The Everest torch, specially designed to burn in frigid, windy, oxygen-thin Himalayan air, is a sister flame to the one that made its way around the world and reached Hong Kong on Wednesday.
In Beijing, officials held a mini-marathon and song gala to commemorate the 100-day mark. Senior Communist Party leader Jia Qinglin urged all Chinese "to pool our patriotic passion to accumulate a mighty force that could overcome all difficulties to in a bid to hold a successful Olympics."
Even before the torch arrived in Hong Kong, authorities deported at least seven people whom they considered a threat to the relay.
Human rights groups accused the government of suppressing free speech to avoid the political embarrassment of demonstrations. Though ruled by China, Hong Kong is supposed to enjoy Western-style civil liberties such as freedom of expression that are denied in the mainland. It grants visa-free entry to many Westerners, raising the prospects of demonstrations.
Mia Farrow was due to arrive in Hong Kong on Thursday to raise awareness about fighting in Sudan's Darfur region. Activists such as the 63-year-old actress want China to press its ally Sudan to let U.N. peacekeepers into Darfur.
The deported activists included three pro-Tibet protesters who were kicked out of the territory as they arrived at the airport Tuesday. A fourth activist - an organizer for an independent Chinese writers' group that calls for freedom of expression in China - also was turned away on Tuesday. Three Danish activists were deported over the weekend.
Hong Kong officials have said repeatedly they won't discuss individual cases.
One of the deported pro-Tibet activists, Kate Woznow, said Tuesday that immigration officials questioned her about her trip but gave no reason for turning her away.
"I really thought that Hong Kong authorities were different from Beijing," she told The Associated Press in a phone call from her plane before it was set to takeoff for New York.
Also on Tuesday, the government of Nepal said it had deported American mountaineer William Brant Holland of Midlothian, Va., for violating regulations by bringing a "Free Tibet" banner to the Mount Everest base camp. It also ordered a BBC news crew out of the camp.
Nepal, wary of hurting relations with Beijing, is trying to enforce a strict ban on protests during China's upcoming Olympic torch relay to the summit of the world's highest mountain.
The relay up Everest will take place on the Chinese side of the mountain. But Nepal's government, under pressure from Beijing, has posted soldiers on its side and banned climbing near the summit from May 1-10.