The President, Mrs Mary McAleese, will fly out to Washington tomorrow morning to attend the funeral service of former US president, Ronald Reagan.
The state funeral will take place on Friday morning. Mr Reagan (93) died last Saturday following a lengthy battle with Alzheimer's disease.
Mrs McAleese will return from Washington DC on Saturday morning.
Reagan died on Saturday surrounded by his his wife, Nancy, and their two children, Ron Reagan and Patti.
His remains are being takento Andrews Air Force Base outside Washington today, from where they were to be transferred to a cortege that will be driven to the center of the capital city.
The casket will be transferred then to a horse-drawn caisson - a two-wheeled military vehicle - that will be driven to Capitol Hill, where his remains will lie in state for 24 hours.
On Friday, a motorcade will transport Mr Reagan's body to the National Cathedral, where the national funeral service will be conducted. Afterward, a motorcade will take the casket back to Andrews Air Force Base, and it will be flown back to California for a private service and a private burial at the library.
Friday has been declared a national day of mourning in the United States.