Reuters journalists at locations across the country reported a mixed election day picture, with some polling stations closing at the planned time of 2:30 p.m. (1330 GMT) while others had yet to open. Some suspended voting after running out of ballot papers.
Independent National Electoral Commission (INEC) officials cited technical problems with a new biometric anti-fraud voter accreditation system, the late arrival of vehicles to transport them and the absence of voter registers as causes of delays.
In a televised news briefing, INEC Chairman Mahmood Yakubu acknowledged the delays but said voters would be able to cast their ballots.
"The election will hold and no one will be disenfranchised," he said.
Though polls in Nigeria officially closed at 2:30pm (1330GMT), voters already in queue are allowed to vote.
"It is frustrating that INEC are not prepared for us. All we want is just to vote," said Sylvester Iwu, who was among a large crowd waiting at a polling station in Yenagoa, the capital of Bayelsa State in the southern oil-producing Niger Delta.
Director General of the World Trade Organisation, Ngozi Okonjo-Iweala, who is from Nigeria's southeast Abia State, tweeted that her polling station was not open three hours into the official voting time.
"The INEC officers finally arrived. My husband and I have just voted," she wrote.
"The turnout is unbelievable, the largest I have ever seen in all the years I have voted in the village."
At one polling station in Lagos, 27-year-old voter, Odinko Ijeoma, said she was hoping for change.
''I can say that the experience has been good because when I came out here I was so impressed with the turn up, so many people came out. They want to take back their country that is why they all turned out to vote. So me, I was excited, like I woke up this morning and I was so excited and I was like history is going to be made today,'' she said.
Hundreds of voters at a polling station in Nigeria’s Kano city saw no signs of voting as they waited without information.
Nafisat Aliyu, a teacher who said she was at the polling unit before the scheduled time, said she was disappointed, while Hashim Adebayo said he remained hopeful and was staying in the queue.
Port Harcourt resident Norbert Okeke, a motor parts salesman, said he would stay as long as necessary.
"I am staying here until I vote with my conscience. Even until 3:00 am I will be here," he said. "The current government has disappointed everyone. We want a new Nigeria."
With seats in the National Assembly also up for grabs, more than 93 million people were registered to vote at some 176,600 polling stations.
The final tally from the 36 states and federal capital Abuja is expected within five days of voting.
Information in this report came from Reuters and Agence France-Presse.
