A rebel leader who seized power in the Central African Republic last month, is now interim president.
Michel Djotodia was chosen on Saturday by the national transitional council, which was set up a week ago. He was the only candidate.
Former President Francois Bozize fled overseas as the rebels advanced.
Mr Djotodia has said he will hold elections within 18 months. The BBC reports he originally said there would be a three-year wait before polls.
The Seleka rebels, an alliance of armed groups, seized power after a peace deal negotiated with Mr Bozize collapsed.
Mr Djotodia is a former civil servant who fell out with Mr Bozize and went into exile, before returning under a peace deal in January as defence minister. He resigned in March.
