Ouattara, whose leadership has helped the West African nation regain a strong economy, is facing a divided opposition - but a partial boycott and voter apathy could result in low turnout.
More than 6 million Ivorians are registered to cast their ballots at around 20,000 polling stations, with voting officially beginning at 7 a.m. (0700 universal time).
However, in a number of locations, voting materials arrived late causing delays.
Voters in the city of Gagnoa and in the Yopougon district of the commercial capital Abidjan were forced to wait for ballots to arrive.
Soldiers, police and gendarmes have been deployed across the country to secure the vote, although the large-scale violence which marred the 2010 election is not expected.
Security has been particularly steped up in Gagnoa, the home region of ex-president Laurent Gbagbo, whose refusal to recognise Ouattara's 2010 poll victory sparked the civil war. He is now awaiting trial before the International Criminal Court charged with crimes against humanity linked to this post-electoral violence.
Leaders of a break-away faction of Gbagbo's Ivorian Popular Front (FPI) have called for a boycott of the polls and their strongholds in the west and in certain parts of Abidjan are potential flashpoints for violence.
Three candidates have joined the FPI in their boycott call by, including former Prime Minister Charles Konan Banny, who pulled out of the vote saying the process was stacked in Ouattara's favour.
Voter turnout will be critical to legitimising Ouattara's mandate if he indeed wins the poll as expected.
Of the six candidates running against him, FPI president Pascal Affi N'Guessan, who is leading his party's moderates, is expected to be his chief challenger.