Mohamed ElBaradei officially became Egypt's vice president of international relations in a ceremony at President Adly Mansour's headquarters in Cairo.
ElBaradei, 71, is a former head of the U.N. International Atomic Energy Agency and received the Nobel Peace Prize in 2005. The MENA news agency said ElBaradei had been seen by some observers as being a candidate for the premiership job during the transition after the ouster of President Mahmoud Morsi by the military.
Installing ElBaradei was an important first step in forming a new government under Mansour. CNN said Interim Prime Minister Hazem El-Beblawi would meet with other Cabinet nominees Sunday and Monday.
Nabil Fahmy, a former ambassador to the United States, told CNN Sunday he had accepted an offer to become Mansour's foreign minister.