Nearly half of the country's 6 million citizens are expected to cast ballots in the election, in which incumbent President Ernest Bai Koroma faces eight challengers, the BBC reported.
Members of Parliament and local councils are also being elected.
Violence tarnished the 2007 elections, and this election will be monitored by several thousand observers, who expect voting this time will be more peaceful.
Koroma won the 2007 presidential election in a runoff, Voice of America reported.
Much in Sierra Leone has changed since the civil war, in which rebels financed their fighting through the illicit sale of what became known as "blood diamonds," The Wall Street Journal reported.
The country's economy will grow 21 percent this year, the International Monetary Fund estimates. Last year, $1.23 billion in direct foreign investment was drawn to the country. In 2010, the investment level was $445 million.
Many of Sierra Leone's young people, who make up 60 percent of the population, are unemployed and ill-educated. Freetown's hillsides are covered with shanties without water, power or sanitation, and prices for consumer goods could rise as much as 11 percent for the year.
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