Gonzales, a former White House counsel, was scheduled to meet Deputy Prime Minister Barham Saleh and visit the Iraqi High Tribunal, U.S. embassy spokeswoman Elizabeth Colton said.
The tribunal is trying Saddam Hussein and six other defendants on charges of war crimes and crimes against humanity.
Gonzales was also to meet with Justice Department officials working in Iraq.
The Attorney General has been criticized in the past for his position on the treatment of non-American prisoners held outside the United States.
He wrote a 2002 memo saying President Bush had the right to waive anti-torture laws and treaties that protect prisoners of war. Critics say that helped lead to abuses in Iraq.