US President Barack Obama will touch down in Canberra at about 3.30pm (AEDT), ahead of a 28-hour visit focused on economic and defence ties with Australia.
The visit comes as security tightens in the national capital, with key roads closed and US Secret Service agents supplementing a bolstered federal police presence.
Mr Obama, America's first black president, will meet Julia Gillard, Australia's first female prime minister, at Parliament House before holding a joint media conference and attending an official dinner.
The president will use a speech to a joint sitting of parliament on Thursday to thank Australia for 60 years of friendship through the ANZUS alliance, and spell out America's renewed focus on the Asia-Pacific region.
Ms Gillard and Mr Obama also are expected to spell out the broad details of a new agreement for US Marines to conduct training and exercises with Australian forces based in Darwin.
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The president will meet and greet troops in Darwin on Thursday afternoon before heading to the East Asia Summit in Bali.
"Australia made overtures to the United States to increase our engagement with the armed forces of Australia and our utility of the training facilities, ranges and so forth that are there," said Admiral Robert Willard, commander of US Pacific Command.
"That was unprecedented, and we're very grateful for that overture."
Any announcements about future US force deployments would be made by Mr Obama, Admiral Willard said.
The president's motorcade will involve up to 45 vehicles, with US Black Hawk aircraft and Australian F-18 Hornet fighter jets patrolling the skies.
Mr Obama, who faces a tough election in 2012, will emphasise the importance of Australia and the Asia-Pacific for reaching his goal of doubling American exports and creating jobs in a US economy with nine per cent unemployment.
Obama will be the fifth US president to visit Australia, following Lyndon Johnson, George Bush, Bill Clinton and his immediate predecessor George W Bush.
Australia's ambassador to the US, Kim Beazley, said Mr Obama and Ms Gillard had a strong personal rapport and a "common international agenda".
"They joke a fair bit about how they were both born in `61; they see themselves as generationally empathetic," he told ABC Television on Wednesday.
Mr Obama's personal history, spending some of his youth in Indonesia, also made him more sensitive to Pacific issues.
"He looks around, knows the strategic geography and looks for compatible people in the area," Mr Beazley said.
MPs have been warned to be on their best behaviour for the president's speech on Thursday.
Speaker of the House of Representatives, Harry Jenkins, has written to Senate president John Hogg issuing a standard reminder to parliamentarians to behave themselves.
Liberal senator Scott Ryan said he hoped Australian Greens leader Bob Brown, who interjected about the Iraq war and terrorism detainee David Hicks during a speech in 2003 by George W Bush, did not "embarrass the country this time".
Labor frontbencher Anthony Albanese said Mr Obama is "certainly the best public speaker" that he had ever seen and he looked forward to cabinet's meeting with him.
Nationals leader Warren Truss said anyone who expected the prime minister, who is at the tail end of a series of global forums, to get a poll bounce from the president's visit was deluding themselves.
"Despite the distractions of the Queen, CHOGM, APEC and now a visit by US president Barack Obama, Julia Gillard can't cover up the widening cracks in her own house," he said.
Labor was bitterly divided on everything from leadership to uranium.
"Once the glow wears off from this presidential visit, Australians will wake up to the same old dysfunctional and incompetent Labor government that has to go."
