Residents of the Sao Tome and Principe voted Sunday to pick the next president for the tiny, impoverished west African archipelago, plagued by chronic instability.
Favourite among the 10 candidates on the ballot is former strongman Manuel Pinto da Costa, who played a crucial role in the quest for independence from Portugal.
After independence was achieved in 1975, Pinto da Costa led the country until 1990, ruling it as a communist one-party state.
Voting was scheduled to start at 0700 (local and GMT), but there were brief delays at several polling stations, an AFP correspondent and local media reported.
Army and roughly 200 police were deployed around the island to monitor the vote, which was running smoothly, local media said, although two small villages blocked their polling stations from opening as a gesture of protest.
Residents in the tiny, western Santa Catarina village put stones on the road to prevent electoral officials from arriving, citing the lack of a phone network as their grievance, national radio said.
In Capela, a central village of 2,000 residents, some staged a minor protest over poor water supply.
At his final campaign rally on Friday, Pinto da Costa told supporters he was confident of a first round win.
Since stepping down in 1990, Pinto da Costa has twice failed to get elected.
Another leading contender is 70-year-old Evaristo de Carvalho, who has served twice as prime minister and is currently the president of the national assembly.
Former journalist turned successful businessman Aurelio Martins is also seen as a strong challenger.
He is the official candidate of the Movement for the Liberation of Sao Tome and Principe/Social Democratic Party which Pinto da Costa co-founded.
Former prime minister Maria das Neves and the country's first female defence minister, Elsa Pinto, are also in the running, both as independent candidates.
There are five other minor candidates on the ballot.
Pinto da Costa's critics charge him with having presided over an oppressive dictatorship, but his campaign pledge to root out corruption seems to have engaged voters.
Island residents are anxious for stability in a country that has seen 18 different prime ministers since the end of the one-party system in 1990 and with 54 percent of the country's 200,000 people described as poor by the UN Development Programme (UNDP).
Many are impatient for the country to start exploiting its oil resources, although diplomatic sources have said commercial production could begin in 2014.
Located near the Equator northwest of Gabon, Sao Tome and Principe is one of the world's poorest countries: foreign aid makes up about 80 percent of its budget.
A total of 92,000 voters have registered to decide who replaces outgoing president Fradique de Menezes, who is not eligible to run again after having completed his second five-year term.
Voting closes at 6:00 pm, with the first results expected later Sunday. If no candidate wins an absolute majority, the election will go to a second round on July 24.