It is the first visit by a senior US official since President Jean-Bertrand Aristide left the country on 29 February after a three-week rebellion.
What is the aim of the visit?
Powell is the first US secretary of state to visit Haiti since 1998
He will also look at international attempts to bring stability to Haiti as well as ongoing humanitarian operations.
Mr Aristide has repeatedly accused the US and France of forcing him into exile.
He has filed a lawsuit in Paris against French and American officials, accusing them of kidnapping him.
But the US and France insist that Mr Aristide agreed to leave the country voluntarily and had signed a letter of resignation.
The BBC’s State Department correspondent says Mr Powell will be hoping his visit puts this argument to rest by conferring more legitimacy on the new Haitian government.
He will also be trying to reassure Haiti’s neighbours about America’s long-term commitment to the country’s future.
What is the current political situation in Haiti?
Haiti’s interim President, Boniface Alexandre, appointed Gerard Latortue as prime minister on 9 March.
The two men installed a new 13-man cabinet which drew criticism from some of the country’s politicians.
Latortue has been criticised for hailing some rebels as “freedom fighters”
Prime Minister Latortue also caused an uproar in Haiti among international human rights groups when he hailed some of the rebels who toppled Mr Aristide as freedom fighters.
A key question remains whether the rebels, who still control much of the north of the country, will be given any political role.
Another is what role, if any, the 14 existing senators will play. They recently announced they will resume their function as the legislative power, although there is no lower house of parliament.
The constitutional position is very unclear, as political power appears to reside with the seven-member “Council of Wise Men” – the ad hoc body set up to oversee the political process towards new elections.
Has the security situation improved?
Some 3,500 peace-keepers are now in Haiti, of whom about 2,000 are from the United States, and the rest from France, Chile and Canada.
They appear to have secured the capital Port-au-Prince, but the rebels are the de facto power in many parts of the country since the existing police force was driven out or fled.
Haiti currently has no army, and it is not clear whether the rebels will be incorporated into a new army or police force.
Is food aid arriving?
Haiti is the poorest country in the Western hemisphere.
Some food from the World Food Programme is getting through to the north of the country, but the situation remains critical.
He said 10 international missions in the last decade had failed because there had been no sustained commitment.
There is to be a meeting of possible donor organisations in June in Port-au-Prince.
Where is Aristide now?
He initially went to the Central African Republic, but later travelled to Jamaica, where Prime Minister Patterson allowed him to stay for up to 10 weeks.
It now seems likely he will travel to South Africa after the elections there and live there.
What has been the reaction within the region?
Leaders of the grouping of Caribbean nations, Caricom, decided to withhold recognition of the interim government in Haiti and said they would not welcome Prime Minister Latortue into the organisation’s fold for the time being.
The leaders criticised Mr Latortue for threatening to end relations with Caricom and for praising the rebels who ousted the government of Aristide.
The Venezuelan president, Hugo Chavez, urged countries in Latin America to follow the example of the Caribbean community and refuse to recognize the new government in Haiti.