Ivory Coast is holding a bitterly contested presidential election, the first since the civil war ended in 2011.
The poll has been marred by prominent opposition candidates pulling out, citing widespread irregularities.
President Alassane Ouattara is running for a second term in the world's largest cocoa producer.
Some 3,000 people were killed in the conflict which ended with Mr Ouattara coming to power in 2011.
The conflict broke out after former President Laurent Gbagbo refused to accept Mr Ouattara's victory in the 2010 election.
Mr Gbagbo was subsequently arrested and is due to stand trial next month at the International Criminal Court (ICC), where he denies war crimes charges.
At the scene: Charlotte Attwood, BBC Africa, Abidjan
President Alassane Ouattara arrived at Lycee Sainte-Marie polling station to chants of "Win in the first round" from his supporters.
He was relaxed and confident as he cast his vote in the upmarket neighbourhood of Cocody of the commercial capital Abidjan.
Smiling alongside his wife Dominique, he praised the smooth and peaceful election so far and urged the people of Ivory Coast to come out and vote.
But not everyone in Abidjan decided to go out and vote.
In Yopougon, a run-down area known to be pro-Gbagbo, the maquis, or bars, were full and blasting out coupe decale, a local style of music that shot to fame in this region during a previous war.
People here told us that there was no-one for them to vote for in this election.
"We're waiting for Gbagbo to come back," said one young man.
Others told us they'd been drinking beer in this bar since this morning because there was no point in this election - "we know who is going to win so we'd rather wait to vote in 2020", one said.
Across the road an elderly man approached us shouting: "I've torn up my voters card because we still don't have the results from 2010. Gbagbo is still in prison so we're still in prison."
Mr Ouattara's main challenger is former Prime Minister Pascal Affi N'Guessan, the candidate of Mr Gbagbo's Ivorian Popular Front.
Three of the 10 opposition candidates, including Charles Konan Banny, another former prime minister, have withdrawn from the election.
They allege that the process has been rigged to guarantee victory for Mr Ouattara, a former senior official at the International Monetary Fund.
The president denies the charge, and called on people to turn out in massive numbers.
Voting was delayed for between two and three hours in some polling stations in both Abidjan and the second city, Bouake, according to reporters for BBC Afrique, which is running a live page in French.
In both cases, the equipment to enable biometric voting, such as special tablet computers, had not been delivered in time, they report.
In the pro-Gbagbo Abidjan district of Yopougon, turnout is low, according to BBC Afrique's Caroline Loyer. She says that the problems with the biometric material have led some to question the integrity of the vote.
The results are not expected for several days.
For several years, Bouake was the headquarters of anti-Gbagbo rebel forces.
Mr Gbagbo portrayed himself as representing "true Ivorians" in contrast to Mr Ouattara, a Muslim who has family ties to neighbouring Burkina Faso.
Under Mr Gbagbo and his predecessors, many northern and Muslim Ivorians said they were prevented from getting ID cards, and taking part in elections.
After refusing to admit defeat in November 2010, Mr Gbagbo was eventually arrested by a combination of French, UN and pro-Ouattara forces in April 2011.
Since taking power, Mr Ouattara has overseen an economic boom but been accused of ignoring atrocities allegedly committed by his supporters, while prosecuting his rivals.