Former HK deputy leader Anson Chan (r) backs the election
A by-election is under way in Hong Kong aimed at putting pressure on China to speed up the move to full democracy.
Five activists triggered the vote by resigning their posts in the Legislative Council (Legco) in January.
The activists want universal suffrage for the election of Hong Kong's chief executive and representatives.
However, correspondents say their move has been rendered almost meaningless by the refusal of pro-Beijing candidates to contest the by-election seats.
Chief executive boycott
Voting opened in the five constituencies at 0730 local time (1130 GMT Saturday).
The BBC's Annemarie Evans in Hong Kong says voter turnout is expected to be only about 25% for a poll that has been criticised as a waste of taxpayers' money.
The five legislators are from two small pro-democracy parties.
One, Alan Leong of the Civic Party, said: "Hong Kong people have been promised universal suffrage when the Basic Law was promulgated in 1990. So I don't see how we should be made to suffer an open-ended wait."
The chief executive and other senior government figures have announced that they will not vote on Sunday.
But Hong Kong's popular former deputy leader, Anson Chan, has backed the election.
There remains no clear date when the Hong Kong public will be able to directly elect their leader and legislators.
Beijing has said that direct election of the chief executive cannot start before 2017 at the earliest and Legco by 2020.
The Basic Law is a mini-constitution drawn up before Hong Kong returned to Chinese sovereignty in 1997.
The chief executive is picked by an 800-member election committee and only half of Legco is directly elected from geographical constituencies.