South Sudan was due to hold a general election in December but it was postponed.
The current President is Salva Kiir of the Sudan People's Liberation Movement (SPLM) party.
The president is elected by popular vote and holds a five-year term.
South Sudan has a population of 11.2 million and around 4.8 million registered voters. In the 2010 presidential election, voter turnout was 58.6%.