Just before noon, Obama took the oath on the steps of US Capitol's West Front decorated in red, white and blue in a spectacular inaugural ceremony watched by an estimated 700,000 people crowding the national mall.
Raising his right hand, Obama placed his left hand on two bibles, one which his idol Abraham Lincoln used for his first inauguration in 1861 and the other, a "travelling Bible" of legendary American civil rights leader Martin Luther King Jr, to take the oath a second time in two days from Chief Justice John Roberts.