1 July 1960
Ghana became the first sub-Saharan country in colonial Africa  to gain its independence on 6 March 1957. On 1 July 1960, Ghana was declared a republic with Kwame Nkrumah as its first President. Though it was declared a republic, the country remained part of the British Commonwealth of Nations. A year later South Africa, under the leadership of H. F. Verwoerd, opted to become a republic. This move, unlike in Ghana, was met with a great deal of concern by the black majority and political organisations. Ghana’s transition to republic was rather uneventful.
References

GhanaWeb,Political History,from GhanaWeb,[online],Available at www.ghanaweb.com [Accessed: 23 June 2014]|Boddy-Evans, A. ‘This Day in African History: 1 July’, from About African History, [online], available africanhistory.about.com (Accessed: 12 June 2013)|South African History Online, ‘The Republic of South Africa is established’, [online], available at www.sahistory.org.za (Accessed: 13 June 2013)