Liberians are choosing a new president in a run-off vote between Vice-President Joseph Boakai and former international footballer George Weah.
Mr. Weah, 51, won the first round, but did not secure the required 50% of the vote for an outright victory.
Legal challenges delayed the vote to replace Ellen Johnson Sirleaf, Africa’s first elected female president.
Turnout appears to be low, but the result is expected to lead to the first smooth transfer of power in 73 years.
More than two million people are eligible to cast their ballots in the nation of 4.6 million people, founded by freed US slaves in the 19th Century.
Polls will close at 18:00 local time (the same time GMT), with the result of the election expected later this week.
The contest between Mr Boakai and former topflight footballer Mr Weah has been a stop-start exercise beset with legal wrangling.
Mr Boakai, 73, has been Liberia’s vice-president for 12 years but does not seem to enjoy the support of his boss.
“This is a great day because it is a test of democracy,” he said after casting his vote.
Mr Weah is hoping that it will be third time lucky.
The former AC Milan and Paris Saint-Germain player defeated Ms Johnson Sirleaf in the first round in 2005 but lost to her in the subsequent run-off.
In the following election’s run-off, in 2011, when he ran as a running mate to the opposition candidate, his coalition boycotted the vote, citing irregularities.
I went to a polling station in a school in Paynesville, outside the capital Monrovia, during the first round of the election. It was bustling with long queues of voters who patiently waited to cast their ballots.
This time, though, they are coming in trickles. It is the same at other polling stations across the capital. And it is not clear why.
Observers say the apparent low turnout could be a result of the legal challenges that delayed the run-off vote, and meant that the campaigning was very brief.
There was some hope though that more voters could turn up at polling stations in the final hours of voting.