The body of Bush Senior, which has been lying in state at the US Capitol, will be moved to the National Cathedral later on Wednesday for the funeral.
His son, former President George W. Bush, as well as former Canadian Prime Minister Brian Mulroney, former US Senator Alan Simpson and presidential historian Jon Meacham, the late President's biographer will deliver eulogies.
President Donald Trump and First Lady Melania Trump will attend the service, the White House was cited as saying by CNN. According to reports, Trump will not speak at the event.
Former US Presidents Barack Obama, Bill Clinton and Jimmy Carter will also be present at the funeral along with their wives.
Bush Sr, who served as the 41st US President between 1989 and 1993, died last Friday at the age of 94. He will be buried in his home state of Texas, alongside his wife, Barbara.
The Prince of Wales, German Chancellor Angela Merkel and Jordan's King Abdullah II were among the world figures present in the US to pay their respects.
Former leaders, including John Major, who was UK Prime Minister for most of Bush Sr's term, were also expected to attend the funeral.
Wednesday was declared a national day of mourning and many government offices and US stock exchanges will be closed.
Another departure ceremony was due to take place at Joint Base Andrews in Maryland. Bush Sr's casket will be taken on the presidential plane dubbed "Special Mission 41" for the funeral process back to Texas.
His casket will then be taken to St. Martin's Episcopal Church in Houston, where the body will lie in repose.
A second service was scheduled for Thursday, after which his body will be taken via a train bearing his name to his final resting place at the George H.W. Bush Presidential Library in College Station, Texas, 160 km from Houston.
He will be buried besides "the love of his life", as he always defined his wife Barbara.
(This story has not been edited by Devdiscourse staff and is auto-generated from a syndicated feed.)