Tunisia is set to hold its second free presidential poll since the 2011 uprising that toppled ex-president Ben Ali and sparked the Arab Spring.
It was brought forward from November after the death in July of Beji Caid Essebsi, the first democratically elected president, who took office in 2014.
Twenty-six candidates, including two women, are running in the election.
It is widely viewed as a test of one of the world’s youngest democracies.
Essebsi won Tunisia’s first free presidential elections in 2014 and was credited with largely maintaining stability in the country during his almost five-year rule.
At 92, he was the oldest sitting president in the world at the time of his death. Essebsi had previously confirmed that he was not planning to run for re-election.
Parliament speaker Mohamed Ennaceur is currently acting as interim president.