France is prepared for the second round of presidential election that could see a socialist winner for the first time since 1988.
In the first round socialist Francois Hollande won 28.6% of the vote, ahead of incumbent Nicolas Sarkozy on 26.2%.
Rising unemployment and the euro crisis have dominated the campaign.
Nicolas Sarkozy says he averted recession and will preserve a “strong France”. Francois Hollande contends the country is in “serious crisis” and needs change.
Polls in mainland France and Corsica will be open from 08:00 to 18:00, with voting stations in big cities remaining open for another two hours.
On Wednesday the two rivals took part in a testy debate, watched by an estimated 17.9 million people, and continued to campaign until Friday.
Francois Hollande – who has long been regarded as favorite – said turnout on election day could affect the result.
Nicolas Sarkozy said no election had ever been so “undecided”.
In the final days, each stepped up his appeals to voters who backed far-right leader Marine Le Pen and centrist Francois Bayrou in the first round.
Marine Le Pen, who attracted 6.4 million voters, has said she would cast a blank ballot but called on supporters to “vote according to their conscience”.
Francois Bayrou, who attracted almost 9% of the first-round vote on 22 April, said he would back Francois Hollande in the second.
The socialist candidate has also been endorsed by hard-left candidate Jean-Luc Melenchon, who won 11% of the vote.
President Nicolas Sarkozy, who has been in office since 2007, has promised to reduce France’s large budget deficit and to tax people who leave the country for tax reasons.
Francois Hollande, for his part, has promised to raise taxes on big corporations and people earning more than 1 million Euros a year.
He wants to raise the minimum wage, hire 60,000 more teachers and lower the retirement age from 62 to 60 for some workers.
If elected, Francois Hollande would be France’s first left-wing president since Francois Mitterrand, who completed two seven-year terms between 1981 and 1995.
It would also be the first time an incumbent president has lost a re-election bid in France since Valery Giscard d’Estaing in 1981.
The presidential vote will be followed by a parliamentary election in June.