For the first time since Mauritania's independence, its citizens will vote for a successor to a democratically-elected president, though a government insider campaigning on a message of continuity is tipped to win.
Polls opened at 7am Saturday in the election to replace President Mohammed Ould Abdel Aziz, 62, who since seizing power in a 2008 coup has positioned himself as an ally of the West in the fight against Islamist militants.
Located on the northwest African coast and bordered to the east by the Sahara Desert and south by Senegal, the country of fewer than five million people gained independence from France in 1960.
Abdel Aziz is stepping aside after serving the maximum two five-year elected terms and has thrown his support behind Mohamed Ould Ghazouani, 62, a former general and defence minister.
Abdel Aziz could however maintain influence behind the scenes, and has not ruled out running again in five years when his term limits reset.
Gilles Yabi, founder of West African think tank WATHI, said Ghazouani would likely continue to rule in Abdel Aziz's mould, but could still surprise.
"Ghazouani is someone who is very discreet. It could well happen that the change is not merely cosmetic," Yabi said.
Five candidates besides Ghazouani are on the ballot. Former prime minister Sidi Mohamed Ould Boubacar, backed by Mauritania's biggest Islamist party, has drawn large crowds on the campaign trail and is considered Ghazouani's rival.
Ghazouani has campaigned on the progress made under Abdel Aziz on economic and security issues. Gross domestic product is growing and will receive a boost when a large offshore gas field starts producing next decade.
Tourists are also starting to return for desert tours after years of staying away following a series of kidnappings in 2009.
In recent years, Mauritania has been spared the attacks by jihadist militants linked to al Qaeda and Islamic State that have devastated other countries in West Africa's Sahel region, including neighbouring Mali and Burkina Faso.
Australian Associated Press