The viewing for Preval, who died Friday aged 74, will be held on Friday at a museum on the Champ de Mars, the capital Port-au-Prince's main park. His funeral is set for Saturday.
The former president died after a cardiac arrest, according to local media reports citing Preval's sister.
With a reputation as an honest and efficient administrator, Preval served as president of Haiti, the poorest country in the western hemisphere, with a long history of political violence, in 1996-2001 and 2006-2011.
A moderate leftist, Preval first served as prime minister to ex-president Jean-Bertrand Aristide from February 1991 until the government was toppled in September that year.
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Following that coup, he sought refuge at the French and Mexican embassies in Port-au-Prince, and eventually joined Aristide in Washington, where he stayed until 1994.
Both Preval and Aristide had enjoyed huge support among millions of impoverished Haitians, many of whom live in the capital's violent slums.
During his 2006-2011 term, Preval's popularity suffered after a massive earthquake struck in 2010, killing more than 220,000 people. Critics said he showed a lack of leadership after the disaster.