Former prime minister Evaristo Carvalho has been elected president of Sao Tome and Principe, the election commission said on Monday, after incumbent Manuel Pinto da Costa dropped out of the race citing voting irregularities in the first round.
Carvalho won 42,058 votes in Sunday's poll, the National Electoral Commission (CEN) said, announcing provisional results.
Only 46 percent of voters voted and of those 18 percent turned in blank or invalid ballots, said CEN chairman Alberto Pereira.
Vice president of the ruling ADI party, Carvalho was guaranteed victory in Sunday's run-off after Pinto da Costa quit alleging irregularities in the first round on July 17, which Carvalho led with 49.88 percent of the vote to Pinto da Costa's 24.83 percent.
Located in the Gulf of Guinea, Sao Tome and Principe is a former Portuguese colony of about 200,000 people.
Carvalho, 75, narrowly lost the last presidential election to Pinto da Costa in 2011. He was prime minister in 1994 and again in 2001-2002, and has also served as president of the national assembly and defense minister.
Pinto da Costa ruled the country as a single-party state from independence in 1975 until 1991. He was president again between 2011 and 2016.
Sao Tome and Principe has 19 oil blocks in its exclusive economic zone and an additional joint exploration zone with Nigeria, but is yet to find any commercially viable oil.