12 July 1975
After a brief period of transitional government Dr Manuel Pinto da Costa, the leader of the Committee for the Liberation of São Tomé and PrÁ­ncipe(CLSTP) became the first president of the newly independent Democratic Republic of São Tomé and PrÁ­ncipe. Two islands in the Gulf of Guinea, straddling the Equator, west of Gabon, formed the country. In 1972, the CLSTP changed its name to MLSTP. During the elections MLSTP won all 16 seats in the National Assembly. The constitution, which was promulgated on December 12, 1975, effectively vested absolute power in the President and the MLSTP became the nations' sole legal political party. Dr Manuel held the position until 1991, when his party suffered defeat in the first democratic election.
References

Manuel Pinto da Costa: website: wikipedia.org.|This week in African history: website: africanhistory.about.com.